The Democratic Party’s rare loss of a congressional seat in its urban heartland Tuesday, accompanied by a blowout defeat in a Nevada special election, marked the latest in a string of demoralizing setbacks that threatened to deepen the party’s crisis of confidence and raise concerns about President Barack Obama’s political fortunes.

Even before the polls closed, the recriminations — something short of panic, and considerably more than mere grumbling — had begun. On a high-level campaign conference call Tuesday afternoon, Democratic donors and strategists commiserated over their disappointment in Obama. A source on the call described the mood as “awful.”

“People feel betrayed, disappointed, furious, disgusted, hopeless,” said the source.