US Democratic presidential contenders Elizabeth Warren and Bernie Sanders clashed over whether he once told a woman she could not become president.
While Sanders emphatically denied he had ever made the remark, Warren refused to back down about what he had said during a private 2018 meeting with her.
The two were seen engaging in a tense discussion after the debate, thus underlining an emerging rift between the progressive contenders as the first voting nears.
During the debate in Iowa, they were also seen disagreeing on foreign policy and trade.
Apart from the two senators, opinion polls showed former Vice President Joe Biden and former South Bend Mayor Pete Buttigieg in an extremely tight race.
Six killed in Swiss bus blaze after person reportedly sets themselves on fire
US says it destroyed mine-laying vessels as Trump warns Iran over strait
Britain working with allies to support shipping through Strait of Hormuz
Wildlife to replace humans on next series of UK banknotes
Five Iranian women's soccer players granted humanitarian visas in Australia
