Will Bernie Sanders do the right thing? And what is that, anyway?

Back then, Clinton was far closer in the delegate count and (depending on which states you count) led Obama in the popular vote. But there was no significant ideological gap between the two, and it was in Clinton’s interest to pacify Obama’s supporters. Today, Sanders’ interest is simple: to make as much of an impact as he can.

Ted Kennedy was in a similar position in 1980. By the time the convention voted, he knew he would never be president. As historian Doris Kearns Goodwin said, “It wasn’t because of age, it was because of Chappaquiddick.” He cared more about the personal and philosophical imprint he would leave on the party than on the success of its nominee that fall. And so he came to the convention more in the spirit of aggression than concession. Kennedy tried to change the rules and flip Jimmy Carter’s delegates. Failing that, he fought to control the platform: He gave the greatest speech of his career — one that never explicitly endorsed the candidate who beat him.

Some argue that Democratic division helped cause Carter’s defeat. Most analysts believe he would have lost even with Kennedy campaigning for him coast to coast. And yet, Clinton’s forces have every reason to fear a sequel.

Here are the choices Bernie Sanders faces as he looks to a convention that will welcome him, honor him, but not nominate him:

• What sort of a platform fight does he wage? Susan Estrich, a longtime Democratic strategist who helped lead Kennedy’s platform efforts, believes that Clinton mostly will give in to Sanders’ demands because “the [official party] platform largely doesn’t matter to voters” and “the lesson of 1968 and 1980 is never have a convention that’s out of control, so better to buy peace with a more liberal platform.” That said, there are positions that Clinton will not be able to accept — Estrich believes that single-payer health care and middle-class tax increases could fall into this category — because they cut against a core principle, or they could hurt her in the fall, or both. The choice for Sanders, then, will be to accept 80 percent of what he wants or to fight for 100 percent. 
• If he fights, how does he fight? Sanders could easily have 40 percent of the delegates. Democratic rules allow 20 or 25 percent of the delegates to produce “minority reports” when the majority beats them on an issue, triggering floor fights that could prove a damaging distraction. Does Sanders encourage his supporters to wage policy battles during prime time — delaying critical business like the acceptance speech? 
• Does he demand a primetime speech just for himself — or also for Mrs. Sanders and key supporters? 
• Does he deliver a full-throated endorsement of the nominee? The question is not whether he will argue against Trump but whether — particularly to “Feel the Bern” die-hards — he will make the case for Hillary Clinton.

Beyond the convention, Democrats disagree about what this contest portends for the party’s future. Andrei Cherny worked for Bill Clinton as the youngest White House speechwriter in history. He says we will see “a more lefty agenda and a more lefty party … there is no more center in American politics, and both parties have decided that the path to victory is amping up your base.”

After eight years in power, partisans can become purists and take winning for granted. Enough liberals abandoned Al Gore for Ralph Nader to make a difference. Clinton supporters fear that some pro-Sanders Democrats could stay home and hurt her prospects.

In Cherny’s view, the swerve left compromises not just the party’s electoral prospects but also policy outcomes. He notes that the Democrats’ criminal justice discussion is now entirely about stopping the police f-rom committing bad acts, but it was aggressive, community-based law enforcement — including in the last Clinton administration — that drove crime to historic lows and protected vulnerable neighborhoods. It was a muscular Democratic foreign policy that launched NATO, saved a divided Berlin, and killed Osama bin Laden.

Democrats could also fall into the tea party trap of making commitments that are impossible to keep. Free college may become the liberal equivalent of eliminating Obamacare: a political pledge that can’t survive the realities of governing. And when a disappointed base fails to get what has been promised, it can retaliate by sending ever-more ideological candidates to office, reinforcing the cycle of disappointment and preventing the compromises that make democracy work.

In 2004, Cherny battled Bob Shrum on the John Kerry campaign, whe-re Shrum was the chief strategist. He still disagrees with Cherny. “Today, the center is more left, moderates have moved to the left,” and the Democrats reflect that,” he contends. Shrum believes that “Sanders is a positive force … he’s inspired a new generation of activists just as the ’60s brought a new generation in.” Shrum believes that these people represent the future of the party and will evolve ideologically. After all, Bill Clinton started as a McGovern voter and moved to a different place.

“Just as Clinton as president represented a correction f-rom the Democratic Party of the 1980s, Sanders as a candidate represents a correction f-rom the 1990s.” Shrum says that regardless of what Sanders does at the convention, Hillary Clinton can use her acceptance speech to unify the party and present a message that reflects their shared concern about economic opportunity.

Frank Luntz, the veteran Republican pollster, sees the situation differently. He says “Republican chaos” is what might enable a “McGovernized, back-to-the-future party” to win. In Luntz’s view, it is only because Republicans “are about to nominate someone even more unpopular than Hillary” that “an old-fashioned interest group party” can succeed. The country hasn’t bought into “the entitlement philosophy”; it is just rejecting the al-ternative.

The next chapter of Democratic politics isn’t about Hillary Clinton vs. Bernie Sanders; that battle has already been resolved. It is the war between Clinton-ism (the pragmatic progressivism that has defined the party since 1992) and Sanders-ism (an unapologetic socialism that is more ambitious, and more risky, than anything the party has proposed since the New Deal). And wars tend to be bloody.