Hillary Clinton is overwhelmingly likely to win the Democratic nomination, but it's been close. So far she's taken 1,768 delegates in primaries and caucuses, while Bernie Sanders has secured 1,497.

The same can't be said for the so-called "invisible primary": the contest for top endorsements, institutional backing, and key staffers. According to FiveThirtyEight's endorsement tracker, Clinton is routing Sanders among party elites: 511 members of Congress or governors have endorsed Clinton; only 13 have endorsed Sanders. So while Sanders has 85 percent as many pledged delegates as Clinton, he has only 2.5 percent as many endorsements from top elected officials.

When Sanders complains that the Democratic establishment is in Clinton's corner, this is the establishment he means. As my colleagues Matt Yglesias and Jeff Stein wrote, "Party elites — including leaders of interest groups whose agenda Sanders has always consistently supported — really have worked against Sanders. Not by cheating, but by exercising the normal channels of influence that influential political actors have at their disposal."

(The one exception to the "normal channels of influence" here was the Democratic National Committee's scheduling of debates to help Clinton, which really was deplorable.)

There are two ways of reading the establishment's preference of Clinton. One — the reading Sanders and many of his supporters prefer — is that it's evidence the game was rigged from the start.

The other reading, however, is that the Democratic establishment's preference for Clinton wasn't inevitable — it emerged from strategic choices that both Sanders and Clinton made; choices that helped and hurt them in different ways, and that foretell the kind of president each would be.

Bernie Sanders didn't lose the establishment. He rejected it.

Party elites are a constituency like any other, and Clinton campaigned hard for their support. Hell, she's spent decades campaigning hard for their support. She's been sending holiday cards to their kids, showing up at their fundraisers, working with them on their bills, meeting with them on their priorities. This is the kind of politics both Clintons excel at.

This is not Sanders's kind of politics, and that's putting it mildly. And it's not because he's an "outsider." Sanders has served in Congress for decades, but he hasn't invested the same kind of time into winning over interest groups and forging deep relationships with his fellow senators. I remember asking a legislator who frequently voted with Sanders who the Vermonter's close friends were in the chamber. He got very uncomfortable. Sanders just isn't a back-slapping, relationship-driven kind of politician.

The results are evident. Clinton, for instance, racked up the endorsements of Vermont's other senator and its governor — even though Sanders overwhelmingly beat Clinton among Vermont's voters.

But the difference runs deeper than personality — it springs from both strategy and ideology. Until this election cycle, Sanders wasn't actually a Democrat. And he was always honest that his refusal to join the party was a criticism of its leadership and its direction. In an interview with Vox, he made the argument clearly:

The Democrats, to a much too great degree, are separated from working families. Are the Democrats 10 times, 100 times, better on all of the issues than the Republicans? They surely are, but I think it would be hard to imagine if you walked out of here or walked down the street or went a few miles away from here and you stopped somebody on the street and you said, "Do you think that the Democratic Party is the party of the American working class?" People would look at you and say, "What are you talking about?" There was a time — I think under Roosevelt, maybe even under Truman — where it was perceived that working people were part of the Democratic Party. I think for a variety of reasons, a lot having to do with money and politics, that is no longer the case.

Sanders has benefited mightily from this argument and the credibility he's built by making it. In an anti-establishment year, His political independence has been core to his brand. He wins liberal-leaning independents frustrated with the Democratic Party because, like them, he's a liberal-leaning independent frustrated with the Democratic Party.

This is the case for Sanders: He isn't like those other Democrats, he isn't tied to their institutions or dependent on their funders, and so he won't betray you the way they have. It's a way he differs not just from Hillary Clinton but also, implicitly, from Barack Obama.

How Sanders 2016 is different from Obama 2008

Clinton's margin among Democratic elites wasn't inevitable, and her advantage wasn't immutable. She started 2008 as the candidate of the Democratic establishment, too, but Obama wooed much of it back from her — he got endorsements from key members of Congress like Ted Kennedy and John Lewis, he won over major interest groups like the AFL-CIO, and he signed up top policy talent everyone thought would side with Clinton.

Obama's ability to work with the power centers of the Democratic Party was part of the case his campaign mounted for why he would be a better president than Hillary Clinton: It showed, the campaign said, that he could play both the inside game and the outside game better than she could.

But this spoke to a deep difference between Obama and Sanders's campaigns. Both ran on a critique of a dysfunctional, even corrupt, political system. But Obama believed in an inside game, while Sanders thinks the very existence of an inside game is part of the problem. Obama's argument was that he would fix the system through dialogue and compromise; Sanders's argument is that he'll overwhelm the system with outside activists, ameliorating the need for compromise with Republicans and moneyed interests.

"The major political, strategic difference I have with Obama," Sanders told Vox in 2014, "is it’s too late to do anything inside the Beltway. You gotta take your case to the American people, mobilize them, and organize them at the grassroots level in a way that we have never done before."

This is Sanders's critique of Obama: He thinks Obama was captured by the existing power centers and funders of the Democratic Party, and it led him to abandon the outside game and turn to an inside game. In Sanders's view, Obama let his grassroots army wither while he cut deals with the insurance industry to pass Obamacare. Sanders has no intention of making the same mistake, and that's part of the reason his supporters love him.

Clinton and Sanders offer two very different theories of how to be a successful president

In contrast to Sanders, Clinton's mastery of the inside game is core to her appeal. Part of how the president gets anything done is winning over his party's elected officials, interest groups, and assorted other power brokers. Jimmy Carter, for instance, was famously disliked by congressional Democrats, and it hamstrung his agenda. By contrast, Obama was able to get every single Senate Democrat to vote for Obamacare, and it's the sole reason the law passed.

The skill Clinton is demonstrating in rolling up the entirety of the Democratic establishment, in other words, is deeply relevant to the presidency. The case for Clinton is that she understands how to work the system we have; the case for Sanders is he won't be corrupted by the system we have, and he'll do his best to turn it into the system liberals want. Which vision you view as more realistic will likely drive which candidate you support.

But this is why it's confusing to hear Sanders complain that the Democratic establishment has opposed him at every step. He made a choice to distance himself from the Democratic Party establishment, and he's developed a theory of politics that requires him to retain that distance.

Over decades, Sanders repeatedly dissed one constituency (Democratic elites) in order to appeal to another constituency (voters who mistrust the Democratic Party). Clinton made the opposite choice. The result is that Clinton benefited from the support of Democratic elites and Sanders benefited from his reputation for independence from Democratic elites.