If Bernie Sanders isn't on the ballot come November, can Hillary Clinton convert his supporters?
"Even if he loses, the movement doesn't stop. We have to keep going from there. Vote third party. Vote for the Green Party. Vote for the Socialist Party. Vote for the Communist Party," a Sanders supporter said at a rally in Chicago.
A new Wall Street Journal/NBC poll suggests one-third of Sanders supporters couldn't see themselves voting for Clinton in the general election.
"I don't think she's a good presidential candidate. I will probably vote independent if Bernie isn't the presidential candidate," another supporter said.
"I'm thinking Jill Stein. I might just write in Bernie," a rally attendee said.
For some Sanders supporters, not even the prospect of a Republican in the White House would cause them to throw their support behind Clinton.
"While I don't want a Trump or a Kasich or any of those Republican candidates in the White House, the political movement has to go on," one said.
But consider this: If Clinton does emerge as the nominee, she has history on her side.
Eight years ago, after a bitter primary defeat, it was Clinton's supporters insisting they wouldn't vote for her rival, Barack Obama.
Ultimately, he was elected by an overwhelming majority of Democrats. "Now I'm asking you to work as hard for Barack as you worked for me," Clinton said in 2008.
Sanders himself has suggested he'd back Clinton if she turns out to be the nominee.
"Hillary Clinton will be an infinitely better candidate and president than the Republican candidate on his best day," Sanders said on ABC in November.
Whether his supporters will — in an election year that has defied all conventional wisdom — is another question.