It’s Nov. 3, 2020. It’s been a long Election Day in Pennsylvania, with new voting machines causing confusion at some polling places, and the closure of others for public health reasons leading to long lines at locations still open. Meanwhile, a huge surge of mail ballots driven partly by coronavirus fears of voting in person means it’s going to take days to count them all and determine who won. But President Donald Trump is already declaring victory. Early, unofficial results make it look like he has won the critical battleground state of Pennsylvania in a landslide. But the election night results are incomplete, with most mail ballots not yet counted. And most Democrats voted by mail, while most Republicans voted in person. Trump isn’t winning. His voters are just being counted first. In the days after the election, as the populous and Democratic Philadelphia region counts its votes, the numbers shift in Joe Biden’s favor, and Trump begins to make false claims of voter fraud and election rigging — echoing conspiracy theories he has promoted for months. One week after the election, votes are still being counted, lawsuits are being prepared, misinformation and partisan attacks are flying. And public trust in the legitimacy of the election is fading, fast. None of this has happened yet. But the experience of this month’s Pennsylvania primary election, coupled with Trump’s increasingly frequent false claims about mail voting, show that it’s not only possible: Without policy changes before November, it is likely, elections officials and voting rights advocates say.