Four years ago, Ethan Felder, a union attorney from Forest Hills, Queens, traveled to suburban Philadelphia in an attempt to get Democrats to the polls. 

Many of them, he recalled recently, couldn't be bothered. They were indifferent to the Democratic candidate, Hillary Clinton and unsure they'd vote.

This year, he's back in the suburbs and has noticed a sea change. While support for President Trump among Republicans is more or less equal to what it was in 2016, the enthusiasm among Democrats has grown dramatically.

"Now I think that there's a much deeper and visceral understanding and feeling about the stakes in the election," said Felder, "for the direction of our country and the world, and the future of democracy itself, quite frankly."