Former Rhode Island Governor Lincoln Chafee on Wednesday entered the race for the Democratic presidential nomination, joining two others in challenging former Secretary of State Hillary Rodham Clinton.

Chafee, a former Republican, announced his bid for the White House during a press conference at George Mason University in Arlington, Virginia.

Chafee, who served alongside Clinton in the Senate, criticized senators who voted for the 2002 resolution authorizing military action in Iraq, saying that they had not done their “homework” on claims that Iraq had weapons of mass destruction. Chafee was the only Republican to vote against the resolution.

In an interview with USA Today, Chafee, 62, expanded on his remarks: “I just don't think the Democratic Party should have – as our nominee – someone who made that mistake.”

“This Iraq war, obviously, angers me,” he added. “We live with it today.”

Clinton, for her part, has called her vote a “mistake, plain and simple.”

Like all of the Democratic candidates, Chafee supports marriage equality. As governor, he signed a gay marriage bill into law.