On top of all the other challenges that pollsters have faced in the past two presidential elections, this year has an additional, potentially significant, complication: a well-known third-party candidate.

Measuring support for third-party candidates has long been a particular challenge for pollsters. But it has been decades since the country has seen a third-party candidate as prominent as Robert F. Kennedy Jr., who has an average of about 10 percent of the vote in national polls.

Historically, polls overstate support for third-party candidates. When it comes to Mr. Kennedy, the biggest question may be by how much.

Consider this: In a two-part experiment conducted by The New York Times and the research firm Ipsos, a seemingly subtle difference across two versions yielded significantly different results for Mr. Kennedy.

What’s more, a candidate who is not on the ballot anywhere — a Times editor picked for inclusion thanks to his generic-sounding name — received a non-negligible share of support, highlighting just how much support for third-party candidates can come down to frustration with major-party candidates and a yearning for more options.

What does this all mean? It’s tempting to interpret these results as ungenerous to both voters and to polling. But the results say something real about how preferences work, and the central conundrum when it comes to third-party candidates. (This experiment is separate from Times/Siena College polling, though it was conducted with the same standards and rigor that we apply to all of our polling.)

In short: Much of what influences third-party candidate support isn’t just a straightforward desire to see that person become president. This poses a challenge for pollsters no matter what they do: Simply by listing third-party candidates, a poll might overstate their support. If a poll doesn’t list them, however, it can’t capture their support at all.

This year, to combat that concern, many reputable pollsters ask both versions of the question: one that poses a simple head-to-head contest between major-party candidates, and one that includes third-party candidates who may be on the ballot.

And which question gets asked first is where the difference comes in.

Question order matters

Here is the longer question asked by Times/Ipsos that includes the full field:

It contains a total of six options: the major-party candidates, the three established third-party candidates who have achieved ballot access in at least one swing state, and our wild card, William Davis, at No. 6.

And this is the shorter question that includes just President Biden vs. Donald J. Trump:

Our experiment worked like this: All respondents were shown both the long and short questions, but half were shown the full list first, and the other half were first shown the two-way race.

Among those who saw the long list first, Mr. Kennedy garnered 7 percent of the vote.

But among those respondents who encountered the head-to-head contest before seeing the full list, Mr. Kennedy’s support shot up six percentage points to 13 percent.

Why the increase, if the questions are the same? There are many factors that can explain this, but it is at least partly related to a phenomenon that pollsters call expressive responding. This is when people might use a survey response to show their frustration or express a particular feeling that’s not exactly what is being asked.

In this case, many respondents seem to be using the second question to convey frustration with the choices for president in the first question, whether or not their answers reflect their full views. When respondents have already been given a chance to express their support for one of the two major-party candidates, they seem to be more likely to register a protest of that first choice with their response to the fuller ballot. Some of the respondents given the longer list first are also probably expressing their frustration with the major-party candidates, but our results help demonstrate that effect is magnified when the longest list of candidates is asked second.

[You can find the full results of the poll, including the exact questions that were asked and how the poll was conducted, here.]

That might also explain why Mr. Davis, the Times editor who has no aspirations for higher office, won the support of about 1.5 percent of respondents, putting him on par with an actual Libertarian Party candidate. His support was only slightly lower among respondents who saw the third-party candidates first — evidence that voter frustration, though less pronounced under that scenario, still exists.

What’s more, Mr. Davis gets 4 percent among voters who feel unfavorably toward Mr. Biden and Mr. Trump.

The effects of this phenomenon show up when looking across many high-quality polls. Among 11 recent national polls, those that listed third-party candidates as the second question generally saw higher support for those candidates when compared with the polls that showed third-party candidates as the first question. (In the latest Times/Siena battleground polls released Monday, Mr. Kennedy was listed in the first question and received 10 percent support across the six states.)

An experiment like this can help us get a rough sense of how much support for Mr. Kennedy, and other third-party candidates, might come from voters expressing their frustration. But it also puts into perspective just how much his support can vary across polls and how hard it is to judge his real support.

It also illustrates some of the limitations surveys face. Pollsters can rely only on what voters tell us, and even voters themselves might not have fully thought through some of these questions.

Are voters consciously telling us they plan to vote for Mr. Kennedy, knowing that in the end they might support one of the two major-party candidates? Probably not. But they might be considering their options at a time when these decisions feel fairly abstract.

Is Kennedy a unique case?

History shows that third-party candidates often poll best in the spring and summer before an election — when everything feels fairly hypothetical — but lose steam as the election nears. Looking back at some of the strongest modern third-party candidates like Ross Perot or John Anderson, they often follow a similar path: strong support early in the race that slowly recedes by Election Day.

There’s at least one reason to believe Mr. Kennedy’s support may last longer: his name. In the Times/Siena battleground polls, we asked his supporters why they planned to vote for him. While most listed distaste for the alternatives as their motivation, for a handful — about 7 percent — his family is exactly why they are supporting him, even as many of his relatives have disavowed his candidacy. As one respondent put it: “Because he is a Kennedy.”

But current conditions are also ripe to have inflated third-party support. The two major-party candidates are deeply unpopular, providing an outlet for the type of expressive responding that pollsters worry about. And in our latest Times/Siena swing state polls, support for Mr. Kennedy appeared weak. Only about 30 percent of his supporters said they definitely planned to vote for him, compared with nearly 80 percent of Mr. Trump and Mr. Biden’s supporters who said they definitely planned to vote for their candidate.

So perhaps Mr. Davis, the Times editor, should not consider giving up his job and hitting the campaign trail anytime soon. But poll consumers should consider that even the best polls are imperfect, and it’s important to understand potential sources of error.

This year, Mr. Kennedy’s support is likely a big one.

The Biden administration has been taking criticism as of late for what some have described as conflicting messaging on key subjects relating to the United States’ top Mideast ally: Israel.

During a daily briefing last week, Fox News White House correspondent Jacqui Heinrich pressed White House press secretary Karine Jean-Pierre about the administration’s attestation to an “ironclad commitment” to Israel while “slow-walk[ing] arms sales.”

Jean-Pierre replied, in part, by reiterating America’s commitment to Israeli security remains “ironclad.”

Meanwhile, President Biden himself pledged that if the Israel Defense Forces incur substantively into the southern Gazan city of Rafah, “I’m not supplying the weapons that have been used historically to deal with Rafah, to deal with the cities – that deal with that problem.”

BLINKEN DELIVERS STRONGEST REBUKE OF ISRAEL YET: ‘GET OUT OF GAZA’

Several lawmakers have taken issue with the administration’s stance, including Rep. Mike Rogers, R-Ala., chair of the House Armed Services Committee, who called the president’s recent tack “another shortsighted decision by Biden that undermines our allies, emboldens our adversaries, and sends the message that the U.S. is unreliable.”

“Our adversaries would love nothing more than to drive a wedge between the U.S. and Israel,” Rogers told Fox News Digital in a statement Friday. “Israel has the right to defend itself against Hamas and Iran.”

Rogers’ counterpart in the Senate, Armed Services Committee ranking member Roger Wicker, R-Miss., also called out Biden over a May 8 Associated Press report that the U.S. indeed paused a shipment of bombs in response to Israel potentially making a decision on a “full-scale assault” on Rafah.

“If Hamas laid down its weapons, the war would be over. But if Israel lays down its weapons, it would be the end of Israel,” Wicker said. 

MIKE PENCE ACCUSES BIDEN OF IMPEACHMENT HYPOCRISY

“Unfortunately, President Biden has this backwards. He has withheld arms for our staunchest ally one day then professed solidarity with the Jewish people the next,” the Magnolia State lawmaker added.

Former National Security Council official Victoria Coates said of the administration’s conflicting messaging, “you can’t have it both ways.”

“You’re going to have to pick a team and put on a jersey and get in a fight. And the administration is desperately trying to please both sides,” Coates said.

“And what they’ve achieved is that both sides are very angry with them. So, you know, it’s it’s just a massive failure both on the policy and the political front.”

Two other GOP senators, Ted Budd of North Carolina and Joni Ernst of Iowa, wrote the White House a detailed letter demanding issue-specific answers from Biden on his comments on arms sales and Rafah.

Some of the questions posed included demands on which types of ammunition are reportedly being withheld, whether any arms withheld were part of those directly approved by Congress in a recent supplemental appropriation, and how such reports square with the president’s April 23 pledge to “make sure that Israel has what it needs to defend itself against Iran and terrorists it supports.”

“Why did your administration fail to notify Congress about this decision to withhold assistance to Israel?” Ernst and Budd asked in the letter. 

“We must give Israel the arms it needs to fight the Hamas terrorists that continue to hold Americans hostage. We call on your administration to immediately restart the weapons shipments to Israel today.”

In a statement, Budd told Fox News Digital one of his constituents, Keith Siegel, remains in Hamas captivity along with seven other U.S. citizens.

“President Biden is making it harder to secure the hostages’ freedom,” Budd said.

Another Republican lawmaker, House Foreign Affairs Committee Chair Michael McCaul of Texas, called the threat of an arms embargo a “dangerous mistake” and “shortsighted.”

On his Fox News program, “Life, Liberty & Levin,” former Reagan Justice Department chief of staff Mark Levin went so far as to say Biden’s actions have renewed “ancient blood libels against Jews.”

Stateside, Biden has condemned the “ferocious surge of antisemitism in America” and said that “there’s the right to protest, but not the right to cause chaos” only after he tried to clean up comments made during a press gaggle where he said, “I also condemn those who don’t understand what’s going on with the Palestinians …”

The administration has been criticized for declining to take a tough stance against criminal acts committed by some anti-Israel agitators on college campuses or call on law enforcement to step in.

In April, 27 Republican senators wrote a letter to Attorney General Merrick Garland and Education Secretary Miguel Cardona to demand an update on any efforts to curb the “outbreak of anti-Semitic, pro-terrorist mobs on college campuses.”

“These pro-Hamas rioters have effectively shut down college campuses and have literally chased Jewish students away from our schools,” the letter reads in part. “The Department of Education and federal law enforcement must act immediately to restore order, prosecute the mobs who have perpetuated violence and threats against Jewish students, revoke the visas of all foreign nationals (such as exchange students) who have taken part in promoting terrorism, and hold accountable school administrators who have stood by instead of protecting their students.”

In response to the protests, Rep. Michael Lawler, R-N.Y., of whose district 90,000 Jewish U.S. citizens call home, drafted the Antisemitism Awareness Act, which successfully passed the House, 320-91, with some “nay” votes falling on grounds the bill would purportedly infringe upon First Amendment rights. Lawler’s office did not respond to requests for comment on this story.

Fox News Digital reached out to the White House for comment but did not receive a response by press time.

Fox News’ Jacqui Heinrich, Bradford Betz, Greg Norman and Andrew Mark Miller contributed to this report.

Michael Cohen, perhaps the most anticipated trial witness in modern memory, took the stand Monday morning in the Manhattan district attorney’s hush money prosecution of Donald Trump. Even before his testimony began, Cohen was the most visible character in the trial save Trump himself.

In the early hours of his testimony, the former Trump attorney covered the National Enquirer’s alleged agreement to “catch and kill” stories that might damage the then-candidate, which like much of Cohen’s expected testimony had been detailed by other witnesses. He then discussed the revelation of the “Access Hollywood” recording that threw the campaign into a tailspin, including Trump’s instructions to spin his comments about sexually assaulting women as mere “locker room talk.”

Cohen testified that it was during the feverish efforts to manage that crisis that he learned that the adult-film actor Stormy Daniels was shopping her story of a liaison with Trump, something that he said would have been “catastrophic” for the campaign. He said Trump ordered him to do what he had to do to keep the story from coming out before the election.

Cohen came across on the stand as responsive, matter-of-fact and unguarded in response to Assistant Dist. Atty. Susan Hoffinger’s low-key questioning.

From the opening arguments, both sides have acknowledged Cohen’s central role in the charges against his former boss, for whom he was an uber-loyal fixer and attack dog. And both sides have taken pains to stress Cohen’s credibility problems to the jury.

The defense in fact has put nearly all its chips on the chances that the jury will reject Cohen’s story, making his coming cross-examination the dramatic centerpiece of the trial. More surprisingly, the prosecution has also peppered its presentation with disparagement of Cohen, whom several witnesses portrayed as a self-interested blowhard.

The most significant instance came during the testimony of Hope Hicks, who related that Trump had told her that Cohen paid off Daniels “out of the goodness of his heart” rather than any direction from him. The prosecution then asked a devastating follow-up: Did that seem in keeping with Cohen’s character? No, Hicks responded, she “didn’t know Michael to be an especially charitable person or selfless person.”

Translation: Trump had reimbursed Cohen and lied to Hicks about it. It may have been this honest and damaging assessment that caused Hicks to break into tears.

The prosecution’s participation in pummeling Cohen was good strategy. It likely lowered the jury’s expectations, decreasing the enormous weight on the shoulders of the government’s star witness.

The jury had to be prepared for a witness whose record comprises multiple criminal convictions, such as the illegal payments at issue in this very trial. The prosecution is betting that having already absorbed the bad news, the jurors can listen to Cohen with relatively open minds.

And here’s the thing about Cohen, in my subjective opinion: It comes through that he is telling the truth.

Yes, he is a strong personality — a native New Yorker through and through — and, yes, he has an enormous ax to grind with Trump, who has remained free (so far) while Cohen went to jail for him. But there’s a difference between a witness with credibility problems, however great, and one who is lying, and divining that distinction is what the jury system is for.

We’ve seen that already in this trial with the testimony of Daniels and David Pecker, the louche tabloid muckraker who described the “catch and kill” scheme. Both gave the defense plenty of ammunition for cross-examination, but both came across essentially as telling the truth.

Cohen has been consistent in his story since he turned traitor on Trump, and his earlier lies are easy to understand in the context of his former sycophancy.

Most important, if the cornerstone of the defense is what will no doubt be a savage cross-examination of Cohen, the foundation of the government’s case is its corroboration of his testimony. Starting with the prosecutors’ smart decision to lead with Pecker, their presentation has been designed to prospectively corroborate Cohen. The jurors will be able to recognize nearly every detail from having heard it before.

Cohen will have to carry a few key details alone, however, the most important of which concern two meetings. One was a January 2017 meeting among Trump, Cohen and Allen Weisselberg, the Trump Organization’s longtime chief financial officer and ultimate loyal fall guy, in which Trump allegedly told the two men to work out a plan to reimburse Cohen. The other is a February 2017 meeting between Cohen and Trump in which the then-president allegedly signed off on reimbursing his fixer with monthly payments camouflaged as a legal retainer.

Strong corroborating evidence of the arrangement can be found in what is probably the most important document in the case: an invoice with Weisselberg’s handwritten annotations explaining how Cohen’s $130,000 payment became $420,000 in reimbursements, including taxes and other considerations.

But as far as the jury is concerned, Weisselberg, who could confirm the arrangement and Trump’s role in it, is nowhere to be seen. That’s because he’s at Rikers Island serving a perjury sentence for lying to protect Trump. In fact, it emerged last week that the district attorney’s office hadn’t even tried to reach the former executive, presumably assuming he would continue to do whatever he could to help Trump.

Weisselberg’s absence is a reminder that prosecutors have to play with the cards they’re dealt. Trump continues to exercise a powerful influence over those in his orbit, and Weisselberg is just one example of a witness the district attorney can’t rely on for that reason.

All of which only heightens Cohen’s importance for the prosecution. This week’s testimony will determine whether his word is strong enough to support a measure of accountability for his former boss.

Harry Litman is the host of the “Talking Feds” podcast and the Talking San Diego speaker series. @harrylitman