A generational divide, seen in newer lawmakers’ impatience with bipartisanship and for colleagues who don’t understand new media, has emerged as one of the deepest rifts within the party.

The Senate minority leader came under heavy fire for the second straight day from Democrats enraged at him for backing a Republican bill to avoid a government shutdown, and fallout appears likely to last well past Friday’s vote.

In failing to demonstrate what they stand for, Democrats fumbled the chance to show why they deserve a return to power, centrists and progressives say.