The ongoing sexism row between Elizabeth Warren and Bernie Sanders headlined the final Democratic debate before voting commences.
Ms Warren was seen appearing to decline a handshake offered by Mr Sanders following the Iowa debate as the two sparred over Ms Warren’s accusation that Mr Sanders told her privately that he did not think a woman could be elected president.
Mr Sanders vehemently denied the accusation.
“Does anybody in their right mind think a woman can’t be elected president?” he asked. “Of course a woman can win.”
With the Democratic field tightly bunched among four leading candidates, the debate offered an opportunity for separation.
However none of the six candidates on stage had the kind of moment likely to reshape the race in the final weeks before voting starts.
Instead, the debate was generally marked by a focus on weighty issues of foreign policy, climate change and how to provide health care for all Americans.
Even when disputes emerged, most candidates quickly pivoted to note their larger differences with Donald Trump.
Mr Sanders did step up his attacks on former vice president Joe Biden over his past support of the Iraq War and broad free-trade agreements.
I’m ready to take on Donald Trump because when he gets to the tough talk and the chest thumping, he’ll have to stand next to an American war veteran and explain how he pretended bone spurs made him ineligible to serve
Senator Amy Klobuchar of Minnesota, who was mired in the middle of the pack, seized on Ms Warren’s shifting positions on health care.
Billionaire Tom Steyer acknowledged making money from investments in the fossil fuel industry, but highlighted his decade-long fight to combat climate change, an issue that came up repeatedly throughout the night.
Pete Buttigieg, the former mayor of South Bend, Indiana, sometimes struggled for attention in a debate that often featured points of conflict between his rivals.
Perhaps his strongest moment came when he described how, as a military veteran who is vocal about his faith, he could stand up to Mr Trump in a general election.
“I’m ready to take on Donald Trump because when he gets to the tough talk and the chest thumping, he’ll have to stand next to an American war veteran and explain how he pretended bone spurs made him ineligible to serve,” Mr Buttigieg said.
“And if a guy like Donald Trump keeps trying to use religion to somehow recruit Christianity into the GOP, I will be standing there not afraid to talk about a different way to answer the call of faith and insist that God does not belong to a political party.”
Several candidates also condemned Mr Trump’s recent move to kill Iran’s top general as well as his decision to keep US troops in the region.
“We have to get combat troops out,” declared Ms Warren, who also called for reducing the military budget.
Others, including Mr Buttigieg, Mr Biden and Ms Klobuchar, said they favoured maintaining a small military presence in the Middle East.
“I bring a different perspective,” said Mr Buttigieg. “We can continue to remain engaged without having an endless commitment to ground troops.”