“Every time you hear people like Joe Biden go out and opine on these issues, you’re going to hear people like Pete [Buttigieg] and people like Bernie say, ‘Yes, but,’ ” a former Obama administration foreign policy adviser told The Hill.

But Biden’s defenders call attacks against the former vice president unfair, pointing to the faulty information released by the Bush administration in the run up to the invasion.

“Anybody who voted for that war, and there were many people including Hillary Clinton and many others, were misled by the administration,” Moe Vela, former senior adviser to Biden and member of the Transparent Business board of directors, said.

“I don’t even know why Bernie Sanders continues to bring it up when he knows that that is not a fair assessment at all,” he continued.