The Democrat from Minnesota's 5th Congressional District is arguably the favorite to win the position, with plenty of high-profile endorsements, and according to The Hill lots of internal support as well. Just behind Ellison is Tom Perez, former secretary of labor.
The biggest quote getting attention Thursday morning came after Ellison was asked about President Donald Trump and whether he would support considering impeachment. Three of his House colleagues have publicly suggested they were open to it, while Democratic House leader Nancy Pelosi said it's too early for that.
"I think that Donald Trump has already done a number of things which legitimately raise the question of impeachment," Ellison said.
He specifically mentioned the Emoluments Clause in the Constitution, which prohibits the president from accepting gifts or titles from a foreign official. Ellison argued the same thing a recent lawsuit is arguing – that when a foreign official stays in a Trump hotel, the president is essentially benefitting, and that's in violation of the Emolument Clause.
The Washington Post says whether that's a legitimate argument – that receiving payment for getting a service is the same as being directly given a gift – is questionable.
"I think we need to begin investigations to, not go after Donald Trump, but to protect our Constitution and the presidency of the United States," Ellison said. "To make sure that nobody can monetize the presidency and make a profit off of it for their own gain."
Ellison was also asked about claims he's anti-Semitic, which often reference his past ties to Louis Farrakhan and Nation of Islam – something he’s since apologized for, saying he was wrong.
"These are false allegations," he said. "And that's why I have 300 rabbis and Jewish community leaders who have signed a letter supporting me. ... I have a long strong history of interfaith dialogue, interfaith communication, and that's why in my own community I have strong support from the Jewish community. So these are smears, and we're fighting back every day."
Ellison also mentioned the recent bomb threats made toward Jewish Community Centers, including two in Minnesota, as well as other incidents targeting Jews in recent weeks.
"We have to stand with the Jewish community right here, right now ... and that's what the Democratic Party is all about," he said.
CNN also did a write-up of the debate, saying the divisions within the Democratic Party were clearly on display during it. The Democratic National Committee will vote Saturday on electing a new chair.
Here's CNN's 90-second wrap-up video of the debate.