Leftwing US presidential hopeful Bernie Sanders assailed frontrunner Joe Biden over his Iraq war vote as commander-in-chief credibility during spiking global tensions took center stage Tuesday at the latest Democratic debate.
With Washington's conflict with Iran as the backdrop, the six candidates sought to make their best case against President Donald Trump, and tangled over who has the best judgment on foreign policy.
"I thought they were lying," Sanders said of the Bush administration's justifications for it in 2002. "I didn't believe them for a moment. Joe saw it differently."
Biden said he acknowledged years ago that it was a "mistake to go to war," but he largely declined to clash with Sanders over Iraq.
Instead, he called for leaving special forces and some troops in the Middle East to patrol the Gulf, pushing back against Sanders's and Senator Elizabeth Warren's call to bring all American forces home.
"I think we need to get our combat troops out," said Warren, who is battling Sanders for the right to wave the progressive flag in the 2020 Democratic race.
With no clear frontrunner emerging yet in Iowa, the candidates took the stage with everything to play for just 20 days before Iowans cast the first ballots of the nomination battle.
But the fireworks expected in the run up to the debate largely failed to materialize in the debate's first third.
While Biden, the 77-year-old establishment candidate, is leading national polling, he and Sanders are in a dead heat in Iowa, followed closely by former South Bend, Indiana mayor Pete Buttigieg and Warren.
Minnesota Senator Amy Klobuchar and billionaire California activist Tom Steyer round out the field for the nationally televised debate in Iowa's capital Des Moines.
Ahead of the Iowa vote, each candidate will be scrambling for a breakout moment that could translate into the first tangible victory in a tight contest.
After avoiding open confrontation so far, the two leading liberals, Sanders and Warren, engaged in open sniping on Monday which carried over to the debate stage.
CNN reported that Sanders told Warren in a private meeting in late 2018, as they both contemplated presidential runs, that he did not believe a woman could defeat Trump.
The 78-year-old Sanders called the report "ludicrous," but Warren then released a statement saying that was indeed what Sanders told her.
Sanders at the debate doubled down: "I didn't say it."
Warren said she "disagreed."
"Bernie is my friend, and I am not here to try to fight with Bernie. But, look, this question about whether or not a woman can be president has been raised and it's time for us to attack it head-on."
Fortified by his showing in recent polls despite suffering a heart attack last November, Sanders has launched an offensive against Biden.
On Tuesday Sanders released a blistering three-minute video attacking Biden for his Iraq vote, support for "disastrous" trade agreements, and calls from years ago to cut Social Security.
"I just don't think that Biden's record is going to bring forth the energy that we need to defeat Trump," Sanders tweeted.
The president meanwhile sought to thrust himself into the spotlight, hosting a campaign rally in neighboring Wisconsin, a key swing state, as Democrats took the stage.
Trump accused Sanders of being "a nasty guy," and mocked Biden for occasional memory issues.
"They haven't been doing great on the debates, I have to tell you," Trump told the faithful at his rally.
The debate risks being overshadowed by a historic political drama: Trump's looming impeachment trial in the US Senate, which, if it begins next week, would force four presidential candidates to stay in Washington serving as jurors in the proceedings instead of winning over undecided Iowa voters.
Polling is tight in Iowa, with Biden at 20.7 percent support and Sanders, Buttigieg and Warren all less than five percentage points back, according to a RealClearPolitics average of recent polls.
Klobuchar, credited with a crisp performance in the previous debate, was well behind, at seven percent. Steyer is at 2.7 percent.