If a Democrat wins the White House in 2020, Joe Biden thinks Mitch McConnell will have an “epiphany” and work across party lines to solve the country’s problems.

Other Democratic candidates have scoffed at that idea, as Biden’s insistence that the impasse in our politics can be solved by persuasion and an aggressive use of the bully pulpit has exposed a rift within the Democratic Party over how hard to press for structural reform—and whether healing is even possible.

“You can shame people to do things the right way,” Biden said at a forum this week in Washington, “A National Call for Moral Revival,” organized by the Poor People’s Campaign.

Biden says the job of the president is to persuade, and that Democrats need to make the case for flipping the Senate in 2020 like they did the House in 2018. If McConnell remains in the majority or minority, Biden would work with him.

To those who think it’s “naïve” to talk about working together, Biden says, “If we can’t get a consensus, nothing happens except the abuse of power by the executive. Zero.”

If the Democrats win the Senate in 2020—a big if—Elizabeth Warren would end the filibuster so McConnell could not block legislation by requiring 60 votes.

“We cannot let him block things the way he did during the Obama administration,” she said at the forum. “I’ve been there when it was one set of rules when President Obama was president and now it’s a different set of rules now that they’ve got Trump in the White House. We can’t do that as Democrats. We have to be willing to get in this fight.”

Norm Ornstein, co-author of It’s Even Worse than It Looks, a book about the failures of Congress, told The Daily Beast that he admires the intellectual rigor in the plans that Warren is presenting—but with the odds of capturing the Senate at less than 50 percent and made harder by West Virginia Democrat Joe Manchin saying he might step down early to run for governor, Warren’s platform would be a non-starter even if she won the White House.

Even if Democrats won the Senate, it would likely be by the slimmest of margins, a seat or two, and not all Democrats would support ending the filibuster, fearing the consequences when they could be back in the minority in two years.

Biden may be under-promising in terms of policy because he knows how hard it is to squeeze anything out of the system with McConnell at its helm. But under-promising has its risks, too—just ask Hillary Clinton.

Biden is presenting himself as someone whose personal relationship with McConnell got the Obama presidency out of some tight spots. He continues to believe that if Democrats approach Republicans with respect, consensus can be achieved.

President Obama responded to those who said he didn’t schmooze enough with McConnell by joking at a White House Correspondents’ Dinner in 2013, “Why don’t you have a drink with Mitch McConnell?”

After Republicans picked up an eye-popping eight seats in the 2014 midterms, more than enough to gain control of the Senate and elevating McConnell to majority leader, Obama changed his tune. “I would enjoy having some Kentucky bourbon with Mitch McConnell,” he said at a post-election press conference. When Justice Scalia died suddenly in March 2015, McConnell refused to fill the seat with Obama’s nominee, Merrick Garland.

The time for bourbon was long gone, and the premise that any goodwill can be reestablished is under assault by Warren and others. The scrutiny Biden faces now is whether the lessons learned from his 40 years in public life are still relevant. On the Senate Judiciary Committee, where he served with the late South Carolina Senator Strom Thurmond, a Democrat-turned-Republican who was known for his early segregationist views, Biden was so solicitous of his aging counterpart that when Thurmond died at age 100 in 2003, his widow asked Biden to deliver the eulogy.

Biden is gregarious and prides himself on getting along with everybody, a quality that today’s Democratic activists are in no mood to appreciate. Speaking to donors at a fundraiser Tuesday, Biden waxed nostalgic about a more “civil” time in American politics when he was able to work with segregationist senators James Eastland of Mississippi and Herman Talmadge of Georgia. Affecting a Southern drawl, he joked that Eastland “never called me boy, he always called me son.”

They didn’t agree on much, but they got things done, he said, adding that he knows the “New Left” calls him old-fashioned, a label that goes back to the ’60s and ’70s.

Democratic presidential contender Cory Booker leveled a blistering attack on Biden, saying, “You don’t joke about calling black men ‘boys,’” tweeting his disappointment that Biden didn’t immediately apologize.

“As a national politician, you can’t be tone deaf,” says Bill Galston, a senior fellow at the Brookings Institution. “There should be a little alarm bell that goes off in your head before you start talking about dead segregationists.”

If only Biden had framed it better, talked about how he abhorred their views on civil rights and explained how he had to work with Southern Democrats to advance the party’s agenda in other areas, and they did it in a civil manner because everybody knew where minds could be changed, and where they couldn’t.

This is the ongoing story about Biden. His experience is rooted in a different moment in American history, and he believes the ways that worked in the past are transferable to our current situation. If a Democrat wins the White House, he says, that Democrat will have to work with McConnell and Senate Republicans to get things done.

Biden’s way may be the only way—the difference between politics as we wish it to be, and how it is.