Democrats have five weeks before a critical deadline to potentially replace the party’s nominee in a key U.S. Senate race that will help decide the majority. While switching candidates late in a race is rare, and even unlikely to happen in this case, it can’t be completely ruled out because of extraordinary circumstances in Pennsylvania.

While Lt. Gov. John Fetterman appeared at a volunteer training event on Saturday, he hasn’t been on the campaign trail for nearly two months since he suffered a stroke just days before he won the May 17 Democratic primary. 

If he’s unable to continue with the campaign for any reason, Fetterman has until Aug. 15 to withdraw from the race and be replaced on the November ballot. According to state law, nominees must withdraw at least 85 days before the general election.

It’s rare for a major party nominee to be sidelined for an extended period of time in the middle of a heated race. GOP Sen. Mark Kirk of Illinois suffered a major stroke in January 2012 but wasn’t up for reelection until 2016. Democratic Sen. Tim Johnson of South Dakota had a major, strokelike event in December 2006 and won reelection nearly two years later. Fetterman is set to face voters this fall.

A campaign spokesman told the Pittsburgh Post-Gazette a few days ago that the lieutenant governor is “feeling really well,” “getting better” and “90 percent back to full strength” and will be “on the campaign trail soon.” The spokesman also said Fetterman is out and about running various family errands. Before Saturday, Fetterman’s public profile had been limited to videos, including one from the hospital soon after the stroke and a more recent fundraising video posted on social media.

“I am feeling so great, and we will be back out on the trail soon,” Fetterman said Saturday in an edited video that was posted on Twitter by the campaign. It remains to be seen whether Saturday’s appearance is the beginning of a return to more robust campaign activities. Fetterman has been scheduled to appear at a private fundraising reception on July 21 with Democratic Jewish Outreach Pennsylvania in Montgomery County. He’s scheduled to do a private Zoom call on July 20 with Indian American civic leaders, according to Politico. But, considering the campaign’s lack of transparency about his health status from the outset — he told Democratic volunteers Saturday that he nearly died — and the paucity of public appearances thus far, it’s possible that scheduled events will change. 

If Fetterman can’t continue, things would certainly get more interesting. While it’s not unprecedented for a party to switch nominees late in a Senate race — New Jersey Democrats infamously swapped out politically damaged Sen. Bob Torricelli at the end of September 2002 — it’s about as rare as a sidelined nominee.  

The Pennsylvania Democratic Party’s bylaws have a section on vacancies, but it does not explicitly mention the U.S. Senate. If the vacancy is treated like a “representative in Congress” vacancy, then the bylaws appear to authorize the State Executive Committee to make and certify a nomination upon a candidate’s withdrawal.

That scenario could get complicated if a replacement has to be chosen. Right now, Democrats aren’t allowing for that possibility.

“Democrats in Pennsylvania and across the country are not only united behind John Fetterman, but excited to have him on top of the ticket,” said Joe Calvello, campaign communications director.

“John Fetterman is the Democratic Party’s Senate nominee. To imply there will be any other scenario is a work of political fiction,” said David Bergstein, communications director of the Democratic Senatorial Campaign Committee.

Pennsylvania is one of Democrats’ two best Senate pickup opportunities in the country. Wisconsin, where GOP Sen. Ron Johnson is running for reelection, is the other one. Republicans need a net gain of just one seat for Senate control.

The Democratic nominee in Pennsylvania is even more important because it’s clear that celebrity doctor Mehmet Oz is politically damaged after enduring millions of dollars in attack ads in the Republican primary. Fetterman led Oz 46 percent to 37 percent in a June 10-13 Suffolk University poll; 50 percent to 44 percent in a June 12-19 bipartisan survey sponsored by AARP; and 48 percent to 44 percent in a June 17-19 poll by Cygnal, a Republican firm. Oz had a 28 percent favorable/50 percent unfavorable rating in the Suffolk poll, compared to Fetterman’s personal rating of 45 percent favorable/37 percent unfavorable.

GOP strategists aren’t too worried because they believe they need only to rally Republican voters behind Oz, rather than persuade independents or Democrats. But even if that’s the case, there’s still work for Republicans to do to help Oz rebound from the primary. 

Some Democratic strategists argue that Pennsylvania is such a large state that the Senate race will largely be played out on television rather than through retail campaigning, lessening any impact if Fetterman is absent from the trail. While other Democratic sources agree to an extent, they argue that to win, Fetterman will have to expand his public profile, including by doing media interviews and participating in a debate to demonstrate he’s up to the job. 

The Pennsylvania Senate race is currently rated Tilt Republican.