Pennsylvania was supposed to be the Democrats’ insurance policy. The state’s Senate seat is currently held by a Republican, but Democratic Lt. Gov. John Fetterman has comfortably led the race since August. If Democrats win Pennsylvania, their chance of winning the Senate would be 81 in 100.¹ It would even allow them to withstand the loss of one of their own Senate seats (say, in Georgia or Nevada) and still retain control of the chamber.

But according to three recent polls, Fetterman’s lead is narrowing. According to Suffolk University and USA Today, Fetterman led by 9 percentage points in June, but a Sept. 27-30 poll gave him a 6-point lead. According to Fox News, Fetterman led by 11 points in July but by just 4 points in a Sept. 22-26 poll. And according to Emerson College, Fetterman was up 5 points in August but just 2 points in a Sept. 23-26 poll. As a result of these and other polls, Fetterman has gone from an 11-point lead in FiveThirtyEight’s polling average on Sept. 13 to a 7-point lead today.

According to the Deluxe version of the FiveThirtyEight forecast, Fetterman’s chances of being the next junior senator from Pennsylvania have diminished, from 83 in 100 as recently as Sept. 24 to 73 in 100 today.

The shift is due in part to Republicans getting off the fence and supporting the Republican candidate, celebrity physician Mehmet Oz. In the July Fox News poll, 73 percent of Republicans said they supported Oz, and 13 percent were undecided. In the most recent Fox News poll, though, 83 percent of Republicans said they supported Oz, and only 4 percent were undecided. Republicans may have been slow to come around to Oz because he isn’t their ideal candidate. Before jumping into politics, he had taken liberal positions on issues such as abortion and gun control. Then, earlier this year, he barely survived a nasty Republican primary against David McCormick and Kathy Barnette. And, according to the most recent Fox News poll, only 38 percent of Oz supporters said they supported him enthusiastically. By contrast, 61 percent of Fetterman supporters said they were enthusiastic about their candidate. 

However, this shift is also because Fetterman is losing support. Per Fox News, he led Oz 58 percent to 30 percent among college-educated voters in July. But in September, Fetterman led just 50 percent to 39 percent among these voters. (By contrast, non-college-educated voters barely changed their minds.) And according to Suffolk, Fetterman led among Black voters 71 percent to 6 percent in June, but that lead shrunk to 56 percent to 22 percent in September (17 percent were undecided). This could be because Republican outside groups have spent at least $20 million in recent weeks on attack ads against Fetterman, focusing in particular on the issue of crime and a 2013 incident in which Fetterman pulled a shotgun on a Black jogger.

Pennsylvania isn’t the only Senate race that has gotten better for Republicans in the past couple of weeks, though: Wisconsin and Nevada look better for the GOP as well. As a result, Democrats’ chances of keeping control of the Senate, which was steadily rising since July, has leveled off and even dipped, from a high of 71 in 100 on Sept. 20 to 67 in 100 today. To be sure, Democrats are still favorites to win Pennsylvania’s Senate seat and the Senate overall. But if Republicans are looking for reasons for optimism, they’re starting to become visible.