Out of President Barack Obama's roughly 30-minute set at the White House Correspondents' Dinner Saturday night, one joke stands out as unusually revealing of how the president thinks about politics.

"Bernie's slogan has helped his campaign catch fire among young people," Obama noted. "'Feel the Bern.' That’s a good slogan. Hillary's slogan has not had the same effect." At that moment, the screen behind Obama displayed this:

Ostensibly, this was a joke at Clinton's expense, at how seemingly thankless and uninspiring her vision of politics is relative to Bernie Sanders's. But given what we know about the Obama administration, it makes more sense to think of it as a tongue-in-cheek compliment, praise of what my colleague Ezra Klein once called Clinton's "audacity of political realism."

What Obama is identifying in Clinton is a belief that political change is hard, that it's thankless, that it's full of false starts and sudden collapses and can begin to resemble a Sisyphean struggle the longer you're in it — but that ultimately doing that hard work is the only way anything gets done, and that dreams like Bernie's of an easier path to bigger change are naïve and harmful.

There was a time when this was a major point of differentiation between Obama and Clinton. In 2008, it was Obama who was, at least in Clinton's view, offering a naïve form of anti-politics, promising to transcend partisanship and forge common ground with Republicans rather than steeling for a fight. But by this year, Obama was implicitly conceding that Clinton had it right all along. "The truth is, in 2007 and 2008, sometimes my supporters and my staff, I think, got too huffy about what were legitimate questions she was raising," he told Politico's Glenn Thrush in January.

In 2016, Obama and Clinton are united in thinking of politics as, in the words of Max Weber, " a strong and slow boring of hard boards" — and doubting anyone who doesn't tell voters how difficult it's going to be.

Obama's problem with the Sanders's theory of politics

By this point, Bernie Sanders's theory of politics is well-known. He wants a political revolution, a mass mobilization of the working classes that will result in robust majorities in Congress for social democratic policies, along with an active grassroots organization that can hold Congress and the president accountable and force them to pass universal health care, free college, and the like.

While Sanders has clearly not succeeded in pulling this idea off — at least this election cycle — it's not a crazy notion. There really are millions of non-voters who are substantially to the left of the current electorate and could increase the viability of left-wing candidates if those candidates found a way to mobilize them.

And there's international precedent for this kind of thing. In most European countries, 19th and early 20th century labor organizing resulted in a strong labor movement and social democratic party that was able to force the implementation of a comprehensive welfare state. In Germany, this happened because of the strength of the social democrats scared conservative leaders like Bismarck into passing social insurance laws. In the UK, it happened because the social democrats won a landslide after World War II and implemented their agenda in one fell swoop. In Scandinavia, it happened because the social democrats allied with agrarian farmers' parties to form a durable majority. But while the details differed, a large-scale working class mobilization really did lead to Sandersian policies getting passed in many countries.

The trouble is that America is not most countries. For one thing, it's never really had a "working class" per se. It's had a white working class, and it's had a black underclass, and the former's racism prevented the two from ever really joining forces in a durable way. Sanders has written that he thinks white supremacy is a tool of capital meant to effect exactly this kind of division, but that implies there was a united working class at any point capable of being divided. The two have always been apart, and the mass migration of working class whites away from the Democratic party since the Civil Rights Act passed suggests they're not uniting anytime soon.

The second difference is that America is not a parliamentary democracy. As soon as Clement Attlee and the Labour Party won the UK general election in 1945, they controlled all the levers of power immediately, and could pass most if not all of their agenda. They passed universal retirement pensions, created the National Health Service, nationalized a fifth of the economy, and implemented a Keynesian economic policy that led to unemployment rarely exceeding 2 percent. The only thing limiting Attlee's ability to effect full socialism was the views of other parliamentary Labour Party members — and even there he could count on considerable party discipline.

By contrast, when Obama entered office in 2009 with the biggest progressive majority in over three decades, he still couldn't pass his agenda because of Senate rules necessitating a 60 vote majority. He needed to compromise with Republicans to pass the stimulus, and even during the brief, six-month period during which he had 60 Democrats, his agenda was subject to veto by conservative Democrats like Ben Nelson and Joe Lieberman, due to Congress's inferior party loyalty relative to other nations' legislatures.

And, of course, unified filibuster-proof government is exceptionally rare. Far more common is divided government, or at least unified but not filibuster-proof government, in which you have to work with the opposition to get anything done.

That means that even if a Sanders-like movement were to elect a president, they'd also need to elect at least 60 reliable progressives to the Senate and House too. That's basically unheard of. Even 60-vote Obama didn't have 60 progressives, and LBJ, Jimmy Carter, and Bill Clinton all had to deal with big numbers of conservative Democrats; Clinton tried to pass universal health care with a Democratic Senate caucus that included Richard Shelby.

The Obama/Clinton theory of politics

So establishment Democrats like Obama and Clinton — who may be sympathetic to Sanders's actual agenda but are skeptical of his European-style plan for passing it — have arrived at a theory of politics that's less romantic but has a better track record of success in the United States. It goes something like this:

American politics is thermostatic. The parties alternate power fairly regularly, and each will be in charge roughly half the time in the medium to long run. If the balance is ever upset, the party losing out will adjust its ideology or coalition to return the system to equilibrium. Because of midterm elections and six-year Senate terms, the alternations of power in Congress and the White House aren't in sync. That means that unified control of government is rare, and filibuster-proof control still rarer. Party polarization has led to more ideologically unified parties, meaning less potential for bipartisan collaboration on ideological goals and more potential for unifying the party caucus around a single agenda. So the thing to do is wait for the time, once every 20 years or so, when your party has unified control, and try to pass as much as you can then, subject to the limits placed by the most conservative members of the Democratic caucus. The rest of the time, do what you can with executive action and pray for leverage points like the 2012 fiscal cliff that let you extract concessions from Republicans.

This story looks a lot more like pushing a boulder up a hill forever and a lot less like the end of The American President. It promises big-but-inadequate progress every couple decades or so, and piecemeal reforms in the meantime, if you're lucky.

Obama timed his service well, in that he came into office during one of the rare moments of unified control, enabling him to rack up achievements like the stimulus, Obamacare, and Dodd-Frank in relatively short order. Clinton got the short end of the stick. While Trump has raised the possibility of Democrats retaking the House, it's still unlikely, and a filibuster-proof Senate majority is really unlikely.

The most probable outcome is that Clinton wins the presidency, Chuck Schumer gets a slight majority in the Senate, and the House remains in Paul Ryan's hands. Maybe some small things gets done, like a childless worker EITC. Maybe if you're really lucky you can get Ryan to play ball on immigration reform. But a carbon tax, or paid maternity/paternity leave, or college debt relief? Forget about it.

But while the outcomes might be more modest, the overall approach is the same one Obama used; she's just been dealt worse cards. Obama's joke, silly as it was, was a recognition that they're on the same page here, that he recognizes she has the temperament for this thankless task, a steadfastness of heart which can brave even the crumbling of all hopes. And it's an implicit admonishment of Sanders for not recognizing these realities.

Watch: President Obama on Bernie Sanders and Hillary Clinton