Sen. Bernie Sanders almost certainly won’t win the Democratic nomination after his string of defeats in recent primaries. So the questions around how and when Sanders will end his campaign aren’t really about electoral math anymore, but are instead connected to deeper questions about policy, the Democratic electorate and Joe Biden and Sanders’s personal goals.

These deeper questions essentially are: Does Sanders have any specific goals that he wants — such as Biden taking up one of his major policy ideas — that he could essentially trade with Biden in exchange for dropping out and endorsing the former vice president? Does Biden, who is now racking up endorsements and winning primaries by huge margins, really need to negotiate with Sanders at all? Does the bloc of around 30 percent of Democratic primary voters that have backed Sanders represent a clear constituency that he actually leads, or will Sanders’s supporters be unenthusiastic about Biden even if Sanders embraces him? Will most of Sanders’s supporters vote for Biden in a general election simply to get President Trump out of office, or does Biden need to accommodate them in some way? And are Sanders’s supporters actually open to any accommodation beyond Sanders being the Democratic nominee?

I can’t really answer any of these questions confidently, and despite what you will read or hear on TV, I’m not sure anyone else knows the answers to these questions either. But one way to think about this is through history. Every competitive nomination process ends with a winner, at least one person who can claim to be the runner-up and some bloc of the party that has lost. So here are some models for how the Biden-Sanders primary could be resolved. These are ordered from the least to most favorable for Sanders:

Sanders and the left get basically nothing

Parallel: The 2000 Democratic primary between then-Vice President Al Gore (winner) and former Sen. Bill Bradley.

Bradley didn’t win a single caucus or primary and earned just 21 percent of the popular vote, so he was obviously in a weaker position than Sanders is now. That said, many Democrats view Trump as an existential crisis and now America has a crisis (the novel coronavirus) that could last until November or beyond. With those concerns, Sanders may have less room to get much from Biden because the growing pressure to leave the race and back Biden may at some point become too strong for him to continue.

So Sanders could get nothing, according to Mark Schmitt, who was a top adviser on Bradley’s 2000 campaign. “Not ‘Godfather II’ nothing, but nothing wrapped in a lovely bow of recognition and respect,” Schmitt said.

Sam Rosenfeld, an expert on party politics who teaches at Colgate University, said, “Biden’s victory came so quickly and with so little in the way of extended trench warfare that it’s true that he likely feels less need to assuage Sanders substantively than HRC [Hillary Clinton] did four years ago.”

In this scenario, Biden would pick a running mate, like Sen. Amy Klobuchar, who is similarly resistant to more left-wing ideas. Biden would basically refuse to adopt any of Sanders’s policies and might block their insertion into the Democratic Party’s official platform at the party’s convention, which is currently scheduled for July 13 to16 in Milwaukee.

Changes to the party platform

Parallel: The 2016 Democratic primary between former Secretary of State Hillary Clinton (winner) and Sanders; the 1976 Republican primary between then-President Gerald Ford (winner) and former California Gov. Ronald Reagan.

In 2016, Clinton and her allies allowed Sanders-backed provisions, including the abolition of the death penalty and a $15 minimum wage, into the party platform. A generation earlier, Ford and his camp used the platform to placate supporters of the more conservative Reagan.

The Democrats put some of Sanders’s less controversial ideas into the platform four years ago. In the 2020 process, he has pushed four far-reaching ideas in particular: a wealth tax, Medicare for All, the mass forgiveness of all student debt and free college for all Americans. The party platform in theory speaks for all Democratic candidates, even ones in swing districts. Those Democrats want to appeal to more moderate voters and are wary of Republicans linking them with socialism (and Sanders). So is there a compromise on the wealth tax or the mass forgiveness of college debt that satisfies Sanders’s allies and, say, more moderate House Democrats? That’s not easy to see. How far will Democrats go, with a GOP eager to cast the entire party as socialists?

Formal policy and/or appointment promises

Parallel: The 2016 Republican primary between Trump (winner) and Sens. Ted Cruz and Marco Rubio and then-Ohio Gov. John Kasich.

In May 2016, as some establishment Republicans were still thinking of ways to prevent Trump from winning the nomination, Trump released a list of people he would consider for Supreme Court seats. Neither Neil Gorsuch nor Brett Kavanaugh were on the initial list, but it was full of conservative legal figures. That list served as essentially a promise to the party’s establishment and conservative wings that Trump would appoint conservative judges to the bench, a key priority of the party. (He has followed through in spades.)

Biden has already promised to pick a woman as his running mate and a black woman as a Supreme Court justice — both attempts to placate other important constituencies in the party (black voters and women). And Biden recently announced that he supported tuition-free public college for Americans in households with incomes of $125,000 or less, moving toward Sanders’s position.

Will he go further? In theory, Biden could promise to appoint some prominent liberals to his administration (Sen. Elizabeth Warren, Sanders himself or some of their allies, for example). He could promise not to appoint people that liberal activists strongly dislike, such as former New York Mayor Michael Bloomberg or basically anyone affiliated with Facebook or Wall Street.

In terms of policy, could Biden, in a general election, commit to some kind of tax on the wealthy that is akin to a wealth tax? (The wealth tax is fairly popular with Americans overall.)

Daniel Schlozman, a political scientist at Johns Hopkins University who focuses on political parties, argued that the left will demand a major federal government response to the coronavirus pandemic if Biden is elected — so the disputes between the party’s left and center-left wings might look much different than they did during the Democratic primary.

“The big left asks of Biden will be on the scale and permanence of government interventions more than on any of the issues in the primary,” Schlozman said.

“Biden is very old and his instincts really do just stem from a different and much more cautious era for [Democratic] domestic policymaking,” Rosenfeld said. “That’s going to matter. That said, it’s important to note that the establishment has itself moved significantly since 2008 … The center of gravity on policy questions has shifted left.”

A leftist vice-presidential nominee

Parallel: The 1996 Republican primary between then-Sen. Bob Dole (winner) and conservative activist Pat Buchanan and businessman Steve Forbes; the 2012 Republican primary between former Massachusetts Gov. Mitt Romney (winner) and former Sen. Rick Santorum and former House Speaker Newt Gingrich; the 2016 Republican primary.

Some in the GOP’s more conservative wing doubted that Dole, Romney and Trump were sufficiently right wing in each of their respective primaries. So all three chose running mates — former Rep. Jack Kemp for Dole, then-Rep. Paul Ryan for Romney, then-Indiana Gov. Mike Pence for Trump — deeply trusted by more conservative Republicans.

This route would be complicated for Biden. In theory, the former vice president could excite the younger and more liberal parts of the Democratic base by picking a running mate who is not Sanders but shares many of Sanders’s positions. But few people close to, or as liberal as, Sanders are governors, senators or otherwise serve in positions that might make them natural candidates for the vice presidency. The most obvious figures, Sen. Tammy Baldwin and Warren, would require Democrats to remove a sitting senator and hope that the party can win a special election to keep that seat.

Let’s focus on Warren for a moment. She presents some obvious advantages for Biden in terms of her policy knowledge and high favorability ratings among Democrats. At the same time, Biden’s campaign messaging has been about electability. Would he choose a left-leaning senator from the Northeast like Warren over a more centrist senator from the Midwest like Klobuchar? Also, can a 77-year-old candidate pick a 70-year-old running mate? Can a Democratic Party that is nearly 40 percent Asian, black or Hispanic run an all-white ticket? Also, it’s not even clear that Sanders’s supporters would be super excited about Warren as the vice-presidential nominee.

Sanders is the vice-president nominee

Parallels: The 1960 Democratic primary between then-Sen. John F. Kennedy (winner) and then-Sen. Lyndon Johnson; the 1980 Republican primary between Reagan (winner) and former CIA Director George H.W. Bush; the 2004 Democratic primary between then-Sen. John Kerry (winner) and then-Sen. John Edwards.

The history of the second-place candidate becoming the vice-presidential nominee illustrates one of the challenges for Sanders — he’s not really viable for arguably the biggest prize a runner-up can reasonably expect. Being second on the ticket is potentially incredibly valuable — Johnson and Bush not only served as vice president but ultimately won the presidency themselves (Johnson obviously in very unusual circumstances). But it’s really hard to imagine Biden choosing Sanders, an even older white man (Sanders is 78), as his running mate.

I don’t think it’s worth trying to predict which of these precedents the Biden-Sanders race will follow — I would expect something more than nothing and less than the vice presidency. But this process is worth watching closely, because it won’t happen all at once. Sanders’s exit from the race, the Democratic convention and the time between Biden’s election (if he wins) and the start of his presidency are all potentially points of negotiation between Biden and Sanders, and the center-left and left wings of the Democratic Party. It will take some time to assess what concessions Sanders and the people who support him come away with.