His vice president, JD Vance, said he “obviously” wouldn’t do it.

His nominee for attorney general, Pam Bondi, agreed there was no way: “The president does not like people that abuse police officers,” she told senators last week.

The Republican speaker of the House, Mike Johnson, gave similar assurances that President Trump would not pardon “violent criminals” — the kind who bashed police officers with pieces of broken furniture or stashed an arsenal of weapons in Virginia to be used if their breach of the Capitol failed on Jan. 6, 2021.

Even public opinion was against Mr. Trump. Just 34 percent of Americans thought he should pardon the Jan. 6 rioters, according to a Monmouth University poll in December.

But on Monday, the first day of the second Trump presidency, he tossed caution aside and did exactly what he wanted: He decreed that every rioter would get some sort of reprieve. It didn’t matter what crimes they committed; whether they were convicted of violent acts or even seditious conspiracy, they will all eventually be cleared. Hundreds of convicts got full pardons; 14 members of far-right groups accused of sedition had their sentences expunged; and all others with ongoing cases will eventually have their charges dismissed.

Mr. Trump’s decision to intervene in even the most violent cases sends an unmistakable message about his plans for power these next four years: He intends — even more so than in his first term — to test the outer limits of what he can get away with.

“These people have been destroyed,” Mr. Trump said of the Jan. 6 rioters, after issuing the pardons, sitting behind the Resolute Desk in the Oval Office for the first time as the 47th president. “What they’ve done to these people is outrageous.”

Mr. Trump’s advisers and lawyers had spent months debating how far he should go in granting clemency to people prosecuted in connection with the Capitol riot. The White House counsel, David Warrington, presented Mr. Trump with options, some more expansive than others, according to two people briefed on the situation who spoke on the condition of anonymity to describe sensitive internal discussions.

Mr. Trump and his advisers had said during the campaign that he would approach the pardons on a case-by-case basis. It was an unspoken recognition that there were dangerous criminals within the group, but the vague formulation was also Mr. Trump’s way of keeping his options open.

He was still making up his mind over the weekend and into Monday, according to advisers. But by Sunday afternoon, people close to him had the impression that he was likely to go for a sweeping form of clemency. To have done anything less would have been an admission that there was something wrong with what his supporters did on Jan. 6, or that cause of overturning the 2020 election was somehow unjustified, or that anyone defending Mr. Trump’s view of the world had erred.

President Biden’s pre-emptive pardons for people who had investigated Mr. Trump’s role in the lead-up to the Jan. 6 assault only added to his desire to take the broadest approach possible, according to the two people with knowledge of his decision-making.

Sitting in the Capitol Rotunda awaiting Mr. Trump’s swearing-in on Monday, one senior member of Mr. Trump’s team said to others, “We can do it all now,” referring to Mr. Biden’s pardons.

The way Mr. Trump sees it, he didn’t only defeat the Democrats in the 2024 campaign; he also vanquished the remnants of Republican opposition, the mainstream media and a justice system that he saw as a force weaponized against him. He has occasionally claimed that the only retribution he wants in office is “success” for the country; but it’s clear from what he has said and done in his first 24 hours on the job that he also wants payback.

The pardons were among several Day 1 actions — some public, some less so — that revealed his plans to get even.

Mr. Trump revoked the Secret Service protection for John R. Bolton, his former national security adviser who fell out with him. Agents had guarded Mr. Bolton since 2021, after U.S. authorities learned of an alleged Iranian plot to assassinate him; a person was criminally charged with targeting him in 2022.

Mr. Trump also revoked Mr. Bolton’s security clearance and that of 49 former intelligence officials who signed a letter before the 2020 election claiming that a laptop belonging to Mr. Biden’s son Hunter appeared to be part of a Russian disinformation operation.

Another of Mr. Trump’s executive orders, lost within the blur of activity on Inauguration Day, suggests an even broader scope for retribution.

The order, titled “Ending the Weaponization of the Federal Government,” has a preamble that asserts as fact that the Biden administration weaponized its prosecutorial powers in pursuing criminal investigations of Mr. Trump and his allies. The order instructs federal agencies, including the Justice Department and the intelligence community, to dig deep to demonstrate the alleged weaponization and then to send reports of the misconduct to the White House. The order sets up what will be, at a minimum, a name-and-shame exercise.

More likely, it will provide a road map for prosecutions.

The White House did not respond to an email seeking comment.

Mike Davis, a Republican lawyer and supporter of Mr. Trump who advocated pardons in connection with the Jan. 6 riot, said the president had learned a great deal about executive power over the past eight years. He said Mr. Trump will not be constrained by people who want to stymie him for what he sees as political reasons.

“This election was a referendum on Trump, on MAGA and on lawfare, and the American people rendered their verdict on Nov. 5,” Mr. Davis said. “He earned power, and now he’s going to use it, like Democrats.”

Mr. Davis was not worried about any backlash to the pardons. “He understands how to govern,” he said, adding that “he knows that public opinion can be changed.”

The Jan. 6 pardons culminated a four-year campaign to rewrite the history of the riot as a day in which Mr. Trump and his supporters were the righteous victims and those investigating their actions were the villains.

That wasn’t always Mr. Trump’s view — or at least not his publicly stated one. The day after the attack, he recorded a video in which he described the assault on the Capitol as “heinous,” adding, “to those who broke the law, you will pay.” This was the second video he released after the riot; his staff thought his first video was too sympathetic to the rioters and they persuaded him to tape another.

In the final days of his first term, Mr. Trump privately discussed the possibility of granting clemency to people involved in the riot. He dropped the idea, but within months of leaving office, Mr. Trump began reframing Jan. 6 as a patriotic day, “a day of love.”

He integrated the “J6 community” into his campaign as patriotic martyrs or, as he called them, “hostages.” Mr. Trump played at his rallies a version of “The Star-Spangled Banner” recorded by a choir of imprisoned Jan. 6 defendants. His nominee for F.B.I. director, Kash Patel, had the idea of turning it into a song, dubbed over with Mr. Trump reciting the Pledge of Allegiance. Mr. Trump still plays the recording on his patio at Mar-a-Lago, as guests stand and sing along, hands over hearts.

Daniel Hodges, one of the officers who was injured on Jan. 6 after being pinned in a doorway of the Capitol and crushed, said Mr. Trump’s whitewashing of Jan. 6 was necessary to preserve his supporters’ belief in their own goodness and patriotism.

“In a way he had to lean into it and say that these insurrectionists were patriots,” said Officer Hodges. If Mr. Trump didn’t elevate the rioters, “they would have to come to terms with the fact that they led an attack against the United States of America — and that’s very antithetical to their self-image.”

The speed with which the mammoth investigation of Jan. 6 collapsed astonished even those who had been mentally preparing for it. Within the space of an evening, not only were nearly 1,600 people granted clemency, but defendants were walking out of prison — among them Enrique Tarrio and Joseph Biggs, two leaders of the Proud Boys serving lengthy sentences for seditious conspiracy.

Ed Martin, Mr. Trump’s new interim U.S. attorney in Washington, was already moving to dismiss riot cases — including the trial of a former F.B.I. agent accused of confronting officers at the Capitol, calling them Nazis and encouraging a mob of Trump supporters to kill them. Mr. Martin sits on the board of the most prominent legal fund-raising group to help Jan. 6 defendants.

Mr. Trump has always favored a maximalist approach toward whatever he does, but he has sometimes stopped short when external constraints seem immovable. It’s unclear, now, how much is left in Washington to restrain him.

He has far more capacity to get what he wants than he did four years ago. He is more knowledgeable about the range of his presidential powers and is far more willing to test them in court. His order to terminate birthright citizenship was something he pushed his administration to do in his first term right up until his 2020 election, but his White House lawyers and his attorney general, William P. Barr, told him he did not have the authority to nullify a right guaranteed by the 14th Amendment.

He now has a more favorable judiciary, which he transformed in his first term, and he has a far more compliant Republican leadership in Congress. Few G.O.P. lawmakers have been willing to say anything critical about Mr. Trump’s pardons of the rioters.

Mr. Trump’s team is also far less of a restraint on his impulses. His second term West Wing contains none of the type of first term aides who tried to talk him out of his most extreme ideas. In their place is a team of loyalists who may occasionally disagree on policy, but are true believers in his instincts, especially after his remarkable comeback.

His team has weeded out anybody they view as disloyal to Mr. Trump. Even people with no known history of opposition to Mr. Trump have been blacklisted because of their associations with Republicans he now views as disloyal. That group includes Republicans he hired in his first term such as Nikki Haley and Mike Pompeo.

Many Trump aides have received subpoenas over the past four years, and some of his closest aides, including his aide Walt Nauta, have been indicted. These investigations further radicalized many of his advisers against what they pejoratively refer to as the “deep state.” Many of them are now joining him in his return to government for this second shot at power. They don’t plan to waste it.