Sen. Michael Bennet (D-Colo.) said Sunday that his fellow presidential candidate former Vice President Joe Biden's support for the war in Iraq was "not his finest hour" in the eyes of some voters.

"I think it is much harder to unite the Democratic party if you voted in favor of the Iraq War, and I think it's much harder to take on Donald Trump, who takes every single position," Bennet said on NBC's "Meet the Press."

"Well you realize I just described Joe Biden. Does that make him less electable than, say, a [Sen.] Bernie Sanders [I-Vt.]?" host Chuck Todd asked Bennet.

"I think that many people would say that was not his finest hour," Bennet responded. "From my vantage point, there's a real question in my mind about whether any of the leading candidates can take on Donald Trump, which is why I've stayed in this race."

"Voters in New Hampshire are more undecided today than they are six weeks ago or six months ago, because they know how much is at stake and they know we need to nominate somebody who can beat Donald Trump he added," saying that as president "I would invite congressional participation in these foreign policy decisions."

Sanders, who opposed the war, has frequently drawn contrasts between himself and Biden on the issue.

"It is appalling that after 18 years Joe Biden still refuses to admit he was dead wrong on the Iraq War, the worst foreign policy blunder in modern American history," Jeff Weaver, a senior adviser to the Sanders campaign, said in a statement late Saturday. "Unlike 23 of his Senate colleagues who got it right, Biden made explicitly clear that he was voting for war, and even after the war started, he boasted that he didn't regret it."