President Biden won the state in 2020 by 1.17 percentage points. That year, Democrats had a larger margin of registered voters compared to their Republican counterparts, at 4.2 million to 3.5 million. The data show that Democrats had a registration advantage over Republicans by 685,818 voters during an election Biden won by 80,555 votes.

The GOP has whittled down that lead this year to a 297,824 margin. When comparing registered voters this election year to 2020, Democrats face a net loss of 257,281 voters, while Republicans have a net gain of 428,537 registered voters. 

More than double the number of previously registered Democrats changed their party affiliation this cycle compared to the number of registered Republicans who left the party: 54,668 registered Democrats changed their party affiliation compared to 25,634 Republicans, Pennsylvania Department of State data shows.