Bernie Sanders told MSNBC's "The Rachel Maddow Show" Wednesday he would drop out of the 2020 race if Joe Biden won a plurality of pledged delegates at July's Democratic convention.

Details: "If Biden walks into the convention, or at the end of the process, has more votes than me, he's the winner," Sanders told Maddow. But he added if it ended up being that a candidate only had a plurality of votes and a second ballot were required that could potentially be decided by superdelegates "it would be a real, real disaster for the Democratic party."

People would say 'the person who won the most votes didn't get selected.' Not a good idea."

What else he's saying: In his interview with Maddow, Sanders said Biden's references to his Obama administration role were "working well" as the former president is "enormously popular" with most Democrats and African American voters.

But he made clear he respected the fact Obama hadn't endorsed any Democratic presidential candidate.

Of note: Sanders made the remarks as he became the latest 2020 candidate to release an ad invoking Obama's image.

Go deeper: Sanders pondered a primary challenge against Obama in 2012