Former President Donald Trump may be facing unexpected challenges in Pennsylvania, where new polling shows a dip in his support among white voters—a crucial demographic in the battleground state.

According to the latest Fox News poll, conducted between October 24 and 28 among 1,310 registered voters in Pennsylvania, Trump is leading white voters by only 4 points, 52 percent to Vice President Kamala Harris’ 48 percent. The poll had a margin of error of plus or minus percentage points.

White voters are central to Trump’s base. In 2016, 54 percent of the demographic voted for him nationally, giving him a 15-point edge over Hillary Clinton, while 55 percent voted for him in 2020, giving him a 12-point advantage. His lead among white voters was just as large in Pennsylvania in 2020, when he won the demographic by 15 points, according to CNN exit polls.

But polls suggest Trump’s white voter base may be shrinking in Pennsylvania. According to AtlasIntel’s latest poll, conducted between October 25 and 29, Trump leads among white voters by just 6 points. The latest CNN/SSRS poll, conducted between October 23 and 28, showed Trump leading among white voters by just 4 points.

Meanwhile, Quinnipiac University’s latest poll, conducted between October 24 and 28, showed Trump leading among white voters by a larger margin, but still by a smaller amount than previous years, with an 11-point lead. Newsweek has contacted the Trump and Harris campaigns for comment via email.

With the national race tight, Trump’s narrowing base of white voters in Pennsylvania could jeopardize his path to victory in the state—and potentially in the overall election. Pennsylvania, with its 19 critical Electoral College votes, has historically been a bellwether, voting for the winning candidate in 48 of the past 59 elections.

Meanwhile, Pennsylvania’s population is predominantly white and working class, with this demographic making up 75 percent of the state’s residents—making it a crucial component of Trump’s base.

Overall, polls remain extremely tight in Pennsylvania. Harris was leading in the Keystone State after becoming the Democratic nominee, but in the last two weeks Trump has taken the lead, according to 538’s poll tracker, which shows Trump with a slim 0.4-point edge. Pollster Nate Silver’s data similarly puts Trump up by 0.6 points, while RealClearPolitics has him leading by 0.7 points.

But there is still potential for the state to flip in Harris’ favor following remarks by comedian Tony Hinchcliffe at Trump’s rally in Madison Square Garden in New York on Sunday that sparked a firestorm of criticism and dominated news headlines.

Hinchcliffe joked that Puerto Rico was a “floating island of garbage.” While Trump campaign adviser Danielle Alvarez said Hinchcliffe’s controversial remarks “do not reflect the views of President Trump or the campaign,” the joke went over badly. The backlash could hit Trump especially hard in Pennsylvania—the swing state with the highest percentage of Puerto Rican residents with 3.7 percent of the population. In 2020, Joe Biden won the state by 1.2 points after Trump won it in 2016.

On the same day as the Madison Square Garden rally, Harris was in Allentown, Pennsylvania, and used the visit to release a video on her plan for Puerto Rico, which Puerto Rican music icon Bad Bunny shared on his Instagram account.

Early voting data from Pennsylvania shows that more Democrats than Republicans have voted, with registered Democrats making up 57 percent of early voters, compared with 32 percent for Republicans, according to the University of Florida’s early vote tracker. It is unclear what this means for the election since the early vote data reveals only whether voters are registered with a party, not who they are voting for.