Leftist Bernie Sanders attacked frontrunner Joe Biden on foreign policy Tuesday but found himself fighting accusations of sexism in the final presidential debate before Democrats begin choosing who challenges incumbent Donald Trump in Novembers election.
With no candidate yet to carve out a clear lead less than three weeks to go before the first votes in the nominations battle, the stakes were high for the six presidential hopefuls on stage in Iowa.
The largely civilized showdown defied earlier expectations of fireworks, with tensions largely held in check during the two-hour debate.
But a rift between Sanders and fellow Senator Elizabeth Warren appeared to widen afterwards when Warren declined to shake hands with her long-time friend and fellow progressive.
The candidates tangled over everything from troop deployments and foreign policy to health care, international trade, climate change and a womans chance of winning the White House.
Sanders, 78, assailed former vice president Biden, 77, over his vote in support of the 2003 Iraq war as the modern-day tensions in the Middle East dominated the opening exchanges.
With Washingtons conflict with Iran as the backdrop, non-interventionist Sanders drew a sharp contrast, saying that while he opposed an Iraq war that was based on lies, former vice president Biden trumpeted the effort.
I thought they were lying, Sanders said of the Bush administrations justifications for war in 2002. I didnt believe them for a moment. Joe saw it differently.
Biden said he had long acknowledged the war was a mistake but refrained from sparring with Sanders over Iraq. Instead, Biden appealed for unity in preventing Trump from winning a second term.
Each candidate is desperate for a breakout moment that could give them the vital momentum heading into the Iowa caucases on February 3 which begins the presidential primary season.
The four candidates in the top tier -- Biden, Sanders, Warren and former South Bend, Indiana mayor Pete Buttigieg -- are bunched together in polling. Senator Amy Klobuchar and billionaire activist Tom Steyer rounded out the debate participants in Iowas capital Des Moines.
For months, Sanders and Warren have battled peacefully for the right to wave the campaigns progressive flag. But their non-aggression pact unravelled in recent days, with Warren endorsing a report that Sanders privately told her he believed a woman could not defeat Trump.