In Pennsylvania, Republican registration is outpacing that of Democrats. Since 2016, the G.O.P. has added more than a hundred thousand registered voters in the state, while the Democrats have lost eighty thousand. The precise meaning of these numbers is somewhat contentious. Democratic strategists point out that their party has registered more first-time voters, and that, over all, Democrats still have about seven hundred thousand more registered members in the state than Republicans do. Still, by any measure, local Republicans have eroded the traditional Democratic lead, mostly by picking off Democrats who have become disaffected. This pattern has been mirrored in other battleground states, such as North Carolina and Florida, where Republicans appear to be closing historic gaps in registration.

In Pennsylvania, the trend is most pronounced in its northeastern corner. In Lackawanna County, registered Democrats have historically outnumbered Republicans three to one, but, over the past several years, the margin has dwindled to two to one, according to Chris Patrick, the local Democratic chair. “To see this flip in this area is extraordinary,” Christopher Borick, a political analyst at Muhlenberg College, in Allentown, told me. Many of the defectors are white voters without college educations. “Even before 2016, you have lifelong white working-class voters in both northeastern and southwestern Pennsylvania who have a ‘D’ on their registration but have been voting for Republicans,” Borick said. Catholic voters in the region are also leaving the Democratic Party, largely because of the Party’s increasingly liberal stance on reproductive rights. “Now you’ve got an Irish Catholic Presidential candidate struggling to win his own town and his own county,” Borick said. (He thought that the recent death of Ruth Bader Ginsburg, and the possibility that a Trump appointee would move to restrict abortion access, might cause more Catholics to defect, though it might also motivate Democratic turnout. “For those voters concerned above all with reproductive rights on both sides, it’s probably a reinforcing issue,” he said.) Cognetti, the Scranton mayor, told me that residents have also become more skeptical of institutions and more sympathetic to Trump’s self-presentation as an outsider. “Basically, every institution of authority in Pennsylvania has let people down in some way in the last decade,” she said. “The sex scandals at Penn State and in the Catholic Church, along with elected officials all over the state going to jail. The absolute crumbling of trust in authority is real, and that can’t be ignored.”

In 2016, the Republican Party noticed that many of these voters, even those who remained registered as Democrats, voted for Trump in large numbers. After the election, the Party began an intensive outreach program, involving canvassing, mailers, and targeted advertising.