The White House may want Charles E. Schumer tossed overboard as the next Democratic leader, but presidents don’t get a vote.

The senior New York Democrat’s opposition to the Iran nuclear deal comes as Schumer looks ahead to an era when Obama will be writing his memoirs and Schumer will set the Senate agenda.

And while Schumer now has a passel of liberal groups — and a posse of ex-White House aides — out to get him, his decision isn’t likely to change his status as the heir apparent to retiring Minority Leader Harry Reid, D-Nev.

That is, unless he somehow succeeds in killing the deal instead of just opposing it. Then all bets just might be off. But according to former Reid spokesman Jim Manley, that’s unlikely.

“That’s not going to happen; that’s hypothetical,” said Manley, who is now a director at QGA Public Affairs. “As in the past, if asked by his colleagues, I expect him to give his opinion, but I can’t imagine he’s going to be out there whipping it hard against it. This is one of these true votes of conscience.”

With several Senate Democrats likely to support the deal, Schumer might alienate his supporters if he launches an aggressive campaign against it. Longtime observers say he is acutely aware of how to count votes.

Deal supporters hoped Schumer would hold off making his position known until it was certain Obama would be able to sustain his veto. This has led to some speculation that Schumer knows the votes are there to sustain a veto.

But the vote is a long way away, and if you take Schumer at his word, he wants this deal dead and will work to persuade his colleagues to kill it. And that could be dangerous to his career.

“He will be crippled as leader if the base hates him, sinking the deal would be the end for him,” tweeted former Obama aide Dan Pfeiffer.

Schumer’s been calling other Democrats to make sure they understand his position, with an obvious subtext of making sure it doesn’t spoil his leadership plans.

A source close to Schumer said none of his colleagues have been surprised by his position and said his explanation of his opposition is measured and policy-driven.

And judging by Schumer’s statement, he is not expected to wield a heavy whip.

“There are some who believe that I can force my colleagues to vote my way,” he said. “While I will certainly share my view and try to persuade them that the vote to disapprove is the right one, in my experience with matters of conscience and great consequence like this, each member ultimately comes to their own conclusion.”

Sen. Claire McCaskill, D-Mo., on “Meet the Press” Sunday said she didn’t think Democrats felt pressured by either Schumer or the White House.

Even if Obama’s veto is sustained, there could be lingering bad blood with Schumer.

Although Justin Barasky, spokesman for the Democratic Senatorial Campaign Committee, said he wasn’t worried about the political fallout, Schumer’s words could certainly be used to criticize Democrats who side with Obama.

Schumer’s already getting lots of love from the GOP presidential candidates, with Sen. Ted Cruz of Texas calling Schumer’s move “fantastic.” And Republican aides and conservative columnists are tweeting lines from Schumer’s voluminous statement with glee.

The anger against Schumer on the left isn’t just over the Iran deal, of course. His coziness with Wall Street, which has made him a fundraiser nonpareil, has always caused heartburn for some.

But that didn’t cause a split with the White House, which also at times has sided with Wall Street against the likes of Sen. Elizabeth Warren, D-Mass.

In recent years Schumer has been plugged in at 1600 Pennsylvania Ave., visiting the White House scores of times, his former aides sprinkled through the administration. (Katie Beirne Fallon is Obama’s chief legislative liaison after serving as a top Schumer staffer. Her husband, Brian Fallon, was top spokesman for Schumer before doing the same for former Attorney General Eric H. Holder Jr. He’s now on Team Hillary.)

What first got Schumer in hot water at the White House was his declaration late last year — out of the blue — that pushing so hard for Obamacare was a political mistake. Now that he’s come out against the president’s foreign policy priority, Obama’s allies aren’t about to forget it.

Former Obama aides Pfeiffer, Tommy Vietor, Jon Favreau and Ben LaBolt Twitter-blasted Schumer within moments of the news breaking. MoveOn.org, quickly followed by other groups on the left, launched a fundraising strike to dump Schumer.

The official White House line was a truism: Schumer’s status as Democratic leader is a decision for senators to make.

But Press Secretary Josh Earnest didn’t hand out praise, either, saying last week, “I wouldn’t be surprised” if senators took voting records into account when making their decision. He highlighted Schumer’s support for the Iraq War for good measure.

He also suggested Schumer had a mindset that minimizes the chances for diplomacy and relies too much on the ability of the United States to impose its will on another country.

Even if the two sides go to the mattresses, the effect is unpredictable. Obama will be preparing for retirement by the time Democratic senators vote on their next leader following the 2016 elections.

Minority Whip Richard J. Durbin of Illinois, an Obama friend, would ordinarily be considered the logical choice to challenge Schumer, his former roommate. He has solid liberal credentials, opposed the Iraq War and was an early backer of the Iran deal. But he quickly endorsed Schumer when Reid announced his retirement, and he isn’t nearly the fundraiser Schumer is.

No. 4 Democrat Patty Murray of Washington also endorsed Schumer and hasn’t ruled out a run against Durbin for the No. 2 post. If she were to change her mind and challenge Schumer, she’d have the chance to make history as the first female party leader in the Senate.

Warren would of course be the dream of the left, but there’s no indication she’d run or be able to beat Schumer, and she doesn’t have the decades of relationships the three top leaders have developed.

Earnest also dismissed the idea Schumer alone would be able to whip enough support for a veto override. He noted that the junior senator from New York, Kirsten Gillibrand, came out for the deal before Schumer.

Much will depend on whether a trend develops of Democratic support for the deal, despite Schumer.

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