Biden and Obama make last-ditch effort as Democrats’ mood darkens

The president has remained outwardly optimistic about Democrats' prospects in Tuesday's midterm elections, but the party is now struggling as polls tighten

The lights dimmed, the music throbbed and cellphone lights danced across the arena. Then a DJ welcomed to the stage the president of the United States, Joe Biden, flanked by the former president Barack Obama and Pennsylvania's nominees for Senate and governor. An ecstatic crowd of thousands roared to their feet.

With days left until the midterm elections, the presidents were in Philadelphia to mobilize Democrats in a pivotal swing state that could determine Congress' balance of power. But the event also had the feel of a political homecoming for Biden, joined by his former running mate in the state where he was born at the end of a volatile campaign season.