Hillary Clinton is virtually certain to be the Democratic Party’s nominee for president. That was true before Tuesday night’s big wins in the Northeast primaries. It’s truer now.

Even Sen. Bernie Sanders (I-Vt .) seems to realize it, based on a statement his campaign released late Tuesday evening.

But Sanders and his supporters have won something too. They have gained influence that is going to shape American politics into the next presidency -- and beyond. That's no small thing.

His fans are understandably disappointed and frustrated with the way the Democratic primaries are concluding. Until relatively recently, winning the nomination seemed possible. And in a year when Republicans are likely to nominate either real estate mogul Donald Trump or Sen. Ted Cruz (R-Texas), winning the general election seemed possible too.

America’s next president could have been a self-described “democratic socialist.” It's a dream that many progressives will find difficult to give up.

But Sanders isn’t going to disappear, no matter what transpires over the next few weeks. Thanks to the 8 million ballots that Democratic primary voters and caucus goers have cast on his behalf, plus whatever Sanders picks up in the remaining contests, the independent senator from Vermont has visibility and a base of popular support.

That means he can make a difference -- far more than seemed possible even a few months ago.

Sanders will have the chance to promote legislation and to help cut deals

So far, Sanders has talked mostly about using his leverage to extract policy promises from Clinton and the party as a whole. In the statement that his team released on Tuesday night, he spoke about the need to carry on his campaign precisely for that purpose -- to make sure he could go “to the Democratic National Convention in Philadelphia with as many delegates possible to fight for a progressive party platform.”

But platforms are symbolic statements of principle. They are not binding pledges to act. The real opportunity to shape policy and politics may take place after the convention and after the general election, when a new president is in the White House and Sanders is back in the Senate.

Sanders will have the chance to promote legislation and to help cut deals -- particularly if Democrats take back the Senate and he ends up as chairman of the Budget Committee, where he is the ranking member. More importantly, he is in line to become a leader of the Democratic Party’s progressive wing, alongside liberal heroes like Sens. Elizabeth Warren (D-Mass.) and Sherrod Brown (D-Ohio).

That means Sanders will have microphones in front of his face every time something consequential happens in Washington. If Clinton becomes president and decides to appoint a Treasury Secretary with close ties to Wall Street, or backs off her pledges on the minimum wage and trade, or cuts some horrendous fiscal deal with Republicans, Sanders can be there to pounce. If a Republican becomes president, he could become an opposition leader in Congress, with a lot of say over where the Democratic Party picks its fights -- and, eventually, who the party nominates to run for president in 2020.

Yes, Sanders has been proposing legislation and speaking out for essentially for his entire career in national politics. But until now, almost nobody in Washington was listening.

His staunchly progressive values and lofty policy ambitions have a large and growing constituency within the Democratic Party.

Sanders would appear regularly on MSNBC shows with brainy hosts and sometimes left-leaning policy writers would feature him in articles. But he rarely had influence, except on veterans' affairs and a handful of other issues over which he had direct committee jurisdiction. To most political professionals, Sanders was a flaky leftist politician from a flaky left-wing state -- in short, somebody they could safely dismiss.

Now Sanders is the guy who ran on an unabashedly progressive agenda and very nearly beat the most experienced and formidable non-incumbent presidential candidate in modern history.

Of course, he can still expect hostility from the political establishment, including members of the Democratic Party. Sen. Charles Schumer (D-N.Y.), who will take over as leader of the Senate Democratic caucus in 2017, is probably thinking up schemes for marginalizing Sanders already. But even to the extent that Sanders ends up on the sidelines, his supporters and his causes are going to command attention.

If the Sanders campaign proved anything, it’s that his staunchly progressive values and lofty policy ambitions have a large and growing constituency within the Democratic Party. Even on Tuesday, amid Clinton’s strong performance, Sanders won more than 70 percent of voters who were younger than 30, according to exit polls. As Matthew Yglesias of Vox noted this month, this is the future of the Democratic Party.

The Sanders candidacy will end soon. But the movement to create a more progressive Democratic Party and, eventually, a more progressive America, is sticking around. And it's getting stronger.