Democratic U.S. presidential candidate Bernie Sanders holds a town hall event at the Navajo Nation casino in Flagstaff, Arizona, March 17, 2016. Reuters/Nancy Wiechec

Vermont Sen. and Democratic presidential hopeful Bernie Sanders said he fully supports President Obama's nominee for the Supreme Court, 63-year-old Judge Merrick Garland. But should Sanders become president-elect in November, he would ask Obama to withdraw his nomination, he said Thursday night in an interview with MSNBC's Rachel Maddow. The self-described Democratic socialist would want a justice who's more progressive than Garland.

Maddow asked Sanders, "If you get the Democratic nomination and you were elected president in November, would you ask President Obama to withdraw that nomination … so you could name your own nominee?"

Sanders' answer was clear. "Yes, I would," he said. "I’m 100 percent prepared to support Judge Garland, I think he’s clearly very knowledgeable and can serve ably on the Supreme Court. But between you and me, I think there are some more progressive judges out there."

The Vermont senator has an increasingly narrow path for earning the Democratic nomination over former Secretary of State Hillary Clinton, however, let alone becoming president. But as a candidate who has earned support by saying he'd take on billionaires, Sanders said his chief concern about a nominee is his or her stance on the 2010 Citizens United v. Federal Election Commission decision, which opened the floodgates for super PAC spending in elections.

"I have said over and over again that I do have a litmus test for a Supreme Court justice," Sanders said to Maddow. "The justice must be loud and clear in telling us that he or she will vote to overturn this disastrous Citizens United Supreme Court decision. I am very worried about the future of American democracy and about the ability of billionaires to buy elections. That is my litmus test and that’s what I would insist on."

Obama announced his nominee Wednesday, saying Garland had drawn support from Republicans before and that “he has shown a rare ability to bring together odd couples.” Republican leadership has indicated they would not hold hearings for anyone Obama puts forth to replace the late Justice Antonin Scalia during this presidential-election year. Earlier in the interview Sanders, while again noting his support for Garland, criticized Republicans for their stance.

"The idea that the president should not be able to make a nomination is totally absurd," he said. "Republican obstructionism just tells us what's been going on for the last seven years. I will do everything I can to see that there [are] hearings and a vote takes place and that Garland becomes seated on the Supreme Court."