WASHINGTON (AP) — President Joe Biden is making a rare jump into the 2024 political battleground fray since taking a step back after ending his reelection bid.

He’ll campaign on Tuesday in Pennsylvania for a close ally and visit Wisconsin to spotlight a signature legislative achievement.

But as Biden makes a quick swing through the key states, two Democratic senators locked in competitive reelection battles are taking markedly different approaches to the outgoing president, whose approval ratings in a significant swath of the country remain in the pits.

Biden will be fully embraced by Democratic Sen. Bob Casey when he participates in an evening campaign fundraiser in Philadelphia for the senior Pennsylvania senator. But in Milwaukee, where Biden is spotlighting his administration’s efforts to replace the nation’s toxic lead pipes, incumbent Democratic Sen. Tammy Baldwin will be conspicuously absent.

“Democrats in tight races, for the most part, are calculating that the risk of embracing Biden far exceeds any reward that his efforts would bring to their campaign,” said Christopher Borick, director of the Muhlenberg College Institute of Public Opinion in Pennsylvania. “There just aren’t many places where he can be of much help to Democrats in competitive races.”

Biden has spent scant time on the campaign trail since ending his reelection effort in July. That makes his stops in Pennsylvania and Wisconsin — two tightly contested states that Vice President Kamala Harris and former President Donald Trump see crucial — all the more notable.

Casey’s and Baldwin’s races are also seen as must-wins for Democrats who are trying to maintain their razor-tight control of the Senate.

Biden, after dropping out, pledged to campaign hard for Harris and Democrats. But as the campaign season has played out, he’s largely stayed on the sidelines as he’s remained a flawed surrogate for Harris and down-ballot Democrats.

Casey, who faces a stiff challenge from Republican David McCormick as he seeks a fourth Senate term, has a long-running relationship with Biden.

Casey grew up on the same street as Biden in Scranton. Their families have known each other for decades, and he’s campaigned with Biden countless times, including earlier this year. Biden — a Delaware resident but a Pennsylvania native — has long claimed Pennsylvania as his own.

Still, Biden faces considerable skepticism and his popularity has sagged amid pessimism about rising costs and doubts about whether at 81 he remains up to the job.

About 4 in 10 voters had a favorable view of Biden and about 6 in 10 had an unfavorable view, according to a Monmouth University poll published in late September.

Baldwin will spend Tuesday on the other side of Wisconsin from Biden, attending campaign events and getting an award, according to her campaign and Senate office.

“Senator Baldwin had a previously scheduled event at a family farm in Eau Claire to receive the American Farm Bureau Federation’s ‘Friend of Farm Bureau’ award recognizing her leadership fighting for America’s hardworking farmers, growers, and producers,” said Eli Rosen, Baldwin’s communications director, in response to a query about why she was skipping the president’s visit.

Biden’s favorability in Wisconsin has hovered around 40% for the past year and did not increase after he dropped out of the presidential race this summer, according to a recent Marquette University Law School poll.

Baldwin, who is seeking her third term, is facing a stiff challenge from Republican Eric Hovde, the CEO of a Wisconsin real estate development company.

She has skipped four of Biden’s five appearances in the state this year, including two in her hometown of Madison, before he dropped out of the race.

However, Baldwin has appeared with Harris, including speaking to a crowd of more than 10,000 people last month in Madison.

“Baldwin may be able to skip a Biden event, but she cannot avoid the verdict of working families in Wisconsin when they head to the polls,” said Wisconsin GOP chairman Brian Schimming.

Biden’s visit to Wisconsin, which has some 340,000 lead pipes, comes as the Environmental Protection Agency on Tuesday issued a final rule requiring drinking water systems across the country to identify and replace lead pipes within 10 years.

Biden’s 2021 infrastructure law provides $15 billion to find and replace the toxic pipes, a legacy the Biden White House says will have an impact on generations to come. Lead can lower IQ and create behavioral problems in children, and the administration believes the legislation will go a long way in removing some 9.2 million lead pipes carrying water to U.S. homes.

White House officials played down Baldwin’s expected absence from the event, while noting that Wisconsin’s other senator, Republican Ron Johnson, voted against the infrastructure law.

“Senator Baldwin is an amazing partner (to) this administration in leading the charge in the bipartisan infrastructure law,” White House deputy chief of staff Natalie Quillian said of Baldwin’s absence from the president’s visit.

Democratic U.S. Rep. Mark Pocan, whose district includes Wisconsin’s deeply Democratic capital city of Madison, said Biden’s policies are popular in the battleground state even if polls show he is not.

“I don’t think that polling on Biden is based on what he’s done in office,” Pocan said. “The problem with some of the polls is overly simplistic. He looks old and people don’t want that in the White House, but he’s not running anymore.”

Pocan, who is not in a competitive race, also defended Baldwin not appearing with Biden.

“If you’re in a competitive race, you have your calendar,” Pocan said. “You have a strategy based on where you’re trying to get votes and you don’t change it when you have a surrogate come.”

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Bauer reported from Madison, Wisconsin. Associated Press writer Linley Sanders contributed to this report.