On Monday, Bernie Sanders and recently elected Democratic National Committee Chair Tom Perez embarked on a "Unity Tour" in several states to rebrand a party now further from power than it’s been in decades.

But serious differences between the Democratic Party’s factions remain. On Wednesday, Sanders and Perez appeared with MSNBC’s Chris Hayes for their first joint interview — and it didn’t take long for Hayes to pry open the split in the politicians’ worldviews.

Chris Hayes pushes Tom Perez to join Bernie in saying "the ruling class & billionaire class" are to blame for our problems. Perez refused. pic.twitter.com/7qiziHLMiX — #AllofUs (@TimeForAllofUs) April 19, 2017

Sanders began the interview by delivering his usual message that Democrats need to clearly communicate to voters that they stand opposed to the “ruling class” he blames for blocking his progressive policy goals:

We can’t bring out about the changes — health care for all, making public colleges and universities tuition-free, transforming our energy system away from fossil fuel — unless we have the guts to point the finger at the ruling class of this country, the billionaire class and Wall Street, and say, “Your greed is destroying this country. And you know what, we’re going to take you on.”

Hayes followed up by asking Perez, sitting next to Sanders, if he agreed with the Vermont senator’s approach. Perez hesitated, and would only commit to accusing Donald Trump — rather than the broader financial elite to which he belongs — of trying to enact an agenda for the “top 1 percent of 1 percent”:

PEREZ: Well, listen, when we put hope on the ballot, we win. When we allow our opponents to put fear on the ballot, we don’t do so well. HAYES: Hillary Clinton ran on hope. It was a very hopeful message. And my point is, do you have to name the enemy? Do you have to say, “These are the people that are screwing you”? PEREZ: I think you’re creating a false choice, Chris. What we have to do as Democrats is articulate very clearly that Donald Trump’s vision for America is a vision for the top 1 percent of 1 percent.

The Democratic Party’s divide over Trump

The Hayes interview exposed two related but separate rifts between Sanders and Perez: 1) whether “billionaires” and the “ruling class” are, in fact, to blame for creating America’s financial problems; and 2) whether blaming them is an effective political strategy that the Democratic Party should collectively pursue.

That Perez and Sanders would diverge on these questions is not surprising. Many supporters of Clinton’s campaign believe she failed not because she declined to attack the rich, but primarily because of outside factors beyond her control — the last-minute letter from FBI Director James Comey; the foreign intervention by Vladimir Putin and WikiLeaks; the archaic nature of the Electoral College. If that’s the case, there’s little need for Democrats to move toward adopting a much more sweeping class-based attack on the rich.

The Sanders wing of the party, by contrast, is much more likely to argue that Clinton failed by running a campaign based too narrowly on attacking Trump’s personality — a campaign that both relied too heavily on wealthy political donors and was unusually lacking in policy messaging around traditional Democratic economic issues.

Sanders tried to slot his ally, Rep. Keith Ellison, into the DNC chairmanship in part to get the committee to administer what he views as his political medicine for the party’s disease. But the party’s old guard, which supported Perez, won. So now the rival Democratic factions are trying to work toward a common goal — erasing Republicans’ grip on congressional power — even as they share radically different understandings of how America got into this position in the first place.