Republican presidential nominee Donald Trump currently has a slight lead over his opponent in the run for the White House.

That is according to elections analyst and FiveThirtyEight founder Nate Silver, who revealed Trump is edging out Vice President Kamala Harris with a 52.4% chance of winning the Electoral College to Harris’ 47.3% chance, according to Silver.

This new model from Silver has the former president in the lead for the first time since Aug 3.

And it appears the Keystone State could be the keystone of the election. 

Silver reported “one big reason” Trump is ahead is Pennsylvania. Silver said Pennsylvania is “the tipping-point state more than one-third of the time” in his model “and where it’s been quite a while since we’ve seen a poll showing Harris leading (including two new polls today).”

Silver’s model also takes into account “a convention bounce adjustment to Harris’s recent numbers” as she rides the high in popularity after the Democratic National Convention.

Harris’ numbers will eventually wane in subsequent weeks, Silver’s model hypothesizes.

That, in addition to her weak polling in Pennsylvania, makes her the underdog in the race.

“There’s another, longer-term concern for Harris, though: it’s been a while since we’ve seen a poll showing her ahead in Pennsylvania, which is the tipping-point state more than a third of time in our model,” Silver said. 

He added, “Today, in fact, we added one post-DNC poll showing Pennsylvania as a tie, and another (conducted during the DNC) showing either a tie or Trump +1, depending on what version you prefer.”

“The model puts a lot of weight on this recent data because of all the changes in the race. And you can see why it thinks this is a problem for her: if she’s only tied in Pennsylvania now, during what should be one of her stronger polling periods, that implies being a slight underdog in November,” Silver said.