For a politician who normally would do anything for publicity or attention, Senator Chuck Schumer has been mighty quiet the last week. The reason isn’t a mystery. The signing of the Iran nuclear deal has put Schumer into a tight spot. As the designated successor to Senate Minority Leader Harry Reid, Schumer is obligated not to lend assistance to the effort to stop a pact that is President Obama’s signature foreign policy achievement. Yet, at the same time, he is under enormous pressure to make good on his past promises to oppose a weak Iran deal and to stand up in defense of the State of Israel, whose security is compromised by the administration’s appeasement policy. Schumer has spent his entire political career positioning himself as an outspoken supporter of Israel as well as a fearsome partisan Democrat. Under most circumstances, that needn’t be a contradiction in terms, but with President Obama lobbying Congress hard to back his deal, they are now. For once, Schumer must choose. But the question is not only what choice will he make but also whether his attempts to keep his feet firmly planted in both the pro-Israel camp and that of the administration can possibly succeed.

Though the administration is seeking with the assistance of left-wing groups to promote the notion that the Iran deal is good for Israel that flimsy argument is deceiving no one. The pact grants Western approval for Iran’s status as a nuclear threshold state enriches it via the collapse of sanctions and provides few safeguards (a 24-day warning period for inspections makes promises about monitoring cheating a joke) against its eventual acquisition of a nuclear weapon once the deal expires. The deal will not only enable Iran to give more support for Hamas and Hezbollah terrorists but will assist Tehran’s goal of regional hegemony.

It is one thing for those whose support for Israel has always been secondary to their left-wing ideology or pro-Obama partisanship (such as the J Street lobby or the National Jewish Democratic Council) to endorse this brazen act of appeasement. For Schumer, a man who has staked his career on being the shomer (Hebrew for guardian) of Israel’s security in Congress, it would be a stunning betrayal that he would never live down.

As I wrote back in April, Schumer’s stance on the Iran deal won’t be the whole story. Even if he chooses to vote in favor of a resolution that seeks to nullify the pact, he may also work behind the scenes to ensure that at least 34 Democrats back the president so as to ensure that an Obama veto won’t be overridden. Such vote trading is routine in Congress and allows House members and senators to tell constituents that they voted one way when they are really conspiring to help those who are working against that goal.

But whether he finesses this vote in that manner or not, it would be mistaken to think that there won’t be serious political consequences for Schumer no matter how he votes.

It may be that the administration will give Schumer a pass for voting against the deal provided that he ensures that other Democrats give the president the votes he needs. But Schumer must also know that his succession as minority leader may be threatened by a vote against Obama. The Senate may be the world’s most exclusive club, but it is entirely possible that his vote will be reason enough for some liberal colleague to challenge him. Any senator that does so will be counting on the active support of the party’s increasingly ascendant left wing that regards Schumer as an ally of Wall Street.

On the other hand, the cost of doing Obama’s bidding could be even higher for Schumer. New York has become a virtual one-party state and Schumer faced only token opposition from Republicans while gaining re-election in 2004 and 2010. But if he were to vote for the Iran deal, it would virtually guarantee that his 2016 re-election race would become very interesting if not competitive. While there is no obvious formidable challenger on the horizon, Schumer knows that the GOP wouldn’t have much difficulty finding one and that such a person would have no trouble raising all the money needed for a race that would become a referendum of Schumer’s possible betrayal of Israel on the Iran nuclear threat.

The first shot fired over his bow comes today in the form of what pro-Israel activists hope will be a massive demonstration in New York’s Times Square. Billed as a “Stop Iran Now” rally, the purpose will be to ensure that Congress knows that the overwhelming majority of the pro-Israel community is united behind the effort to oppose the deal.

If Schumer, and other pro-Israel Democrats stick with Obama they will be allying themselves with J Street over AIPAC, a strategic decision that would be the moral equivalent of choosing a water pistol to use in a fight with a tank when it comes to future electoral support.

But the real problem for Schumer and other Democrats goes beyond the danger of alienating pro-Israel donors. Only those so blinded by their support for Obama fail to see that the Iran deal vote is one of those rare Congressional decisions that present a clear moral choice. If Schumer sticks with Obama, that may secure his future as the Democrats’ Senate leader. But if will come at the cost of his reputation as a defender of Israel and make his seat a lot less safe than it might otherwise be.