“I was holding on to my Republican card, literally and metaphorically, with a firm grasp,” said Arnell, 48. “And I just sat down at the computer one day and I just went on the Chester County website and that’s it.

“I’m done,” she said. “I’m disgusted.”

Arnell represents the political transformation of Philadelphia’s suburbs, now largely Democratic and mobilizing against Trump in the final six weeks before the election. While Trump narrowly won America’s suburbs in 2016, Hillary Clinton swept Philadelphia’s four collar counties. It wasn’t enough to stop Trump from narrowly winning the state, and with it the White House. But people like Arnell who had been slowly walking away from the party in these onetime Republican strongholds broke into a sprint after 2016, and they haven’t looked back…

There’s little doubt that Democratic nominee Joe Biden will defeat Trump in the Philadelphia suburbs. The question is whether he’ll do so with big enough margins. Voter registration trends and interviews with dozens of voters over the last two months suggest Trump retains strong political support in the longtime Democratic bastions in small Rust Belt towns throughout northeastern and southwestern Pennsylvania that he won in 2016.