In the first one-on-one Democratic primary debate Sunday, former Vice President Joe Biden vowed to pick a woman Vice President and promised to appoint a black woman to the Supreme Court. When asked about his plans for a running mate, Vermont Senator Bernie Sanders said that “in all likelihood” he would also pick a woman, but that his running mate would be a progressive.

“I commit that if I’m elected President and I have an opportunity to appoint someone to the courts, I’ll appoint the first black woman to the Court,” said Vice President Biden, meaning the Supreme Court. “If I’m elected President, my cabinet and my administration will look like the country, and I commit that I will in fact pick a woman to be Vice President. There are a number of women who are qualified to be president tomorrow. I would pick a woman to be my vice president.”

This was the first time that Biden, who became the Democratic frontrunner after victories in Michigan and Washington last week, has definitively promised to pick a woman running mate. The promise rules out the possibility of a ticket that includes recent male endorsers like Senator Cory Booker or South Bend Mayor Pete Buttigieg. Former presidential candidate Andrew Yang joked on Twitter that Biden “didn’t mention that to me when we spoke” and added a smiley emoji.

For several minutes, moderator Dana Bash attempted to ask Senator Sanders whether he, too, would promise to select a woman Vice President. At first Sanders tried to confront Biden about his previous support for the Hyde Amendment, which blocks federal funding for abortion, and touted his voting record from NARAL. Finally, Bash was able to directly ask him whether he would pick a woman running mate.

“In all likelihood, I will,” Sanders said. “For me, it’s not just nominating a woman, it’s making sure that we have a progressive woman and there are progressive women out there, so my very strong tendency is to move in that direction.” This essentially ruled out the possibility that if nominated, Sanders would pick a moderate running mate who might appeal to Biden voters and unite the party.

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Write to Charlotte Alter at charlotte.alter@time.com.