By Aahmer Madhani and Scott Bauer, AP

MILWAUKEE, Wis. (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 stopped in Wisconsin on Oct. 8 to spotlight a signature legislative achievement.

In Milwaukee, where Biden spotlighted his administration’s efforts to replace the nation’s toxic lead pipes, incumbent Democratic Sen. Tammy Baldwin was 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 stop in Wisconsin — a tightly contested state that Vice President Kamala Harris and former President Donald Trump see as crucial — all the more notable.

Baldwin’s race is also seen as a must-win 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.

Baldwin was spending Oct. 8 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 in July, according to the Marquette University Law School poll.

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

She 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 in September 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, came as the Environmental Protection Agency on Oct. 8 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.

Biden used his speech in Milwaukee to take digs at Trump and Johnson, but he tactfully kept Baldwin out of his remarks. Still, Milwaukee County Executive David Crowley in his remarks credited Baldwin, along with Biden and Harris, for the lead pipe removal.

Going back to a stock line, Biden noted that Trump routinely had “infrastructure week” during his own presidency but “he didn’t build a damn thing.”

The president’s appearance was also a touch wistful as Crowley and Wisconsin Gov. Tony Evers lavished praise on Biden for being a strong partner for Milwaukee, a city that Trump once called a “horrible city.”

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.”

Biden’s wife, Jill, is scheduled to campaign for Harris in Madison the following week as part of a five-day effort by the first lady through the battleground states of Arizona, Nevada, Michigan, Wisconsin and Pennsylvania, Harris’ campaign and the White House announced Oct. 8.

Bauer reported from Madison, Wisconsin. Associated Press writers Linley Sanders and Matthew Daly in Washington contributed to this report.