Filibuster in haste, repent at leisure. Senate Democrats blocked an amendment from a floor vote that would have required Iran to release all Americans detained in their country and a formal recognition of Israel’s right to exist before Barack Obama’s nuclear deal could go into effect. Republicans only got 53 votes to move forward to a floor vote, setting up a potential fight over the future of the filibuster itself:

Democrats on Thursday blocked a last-ditch effort from Republicans to stop the Iran nuclear deal by linking the agreement to Israel and American prisoners.

Senators voted 53-45 on an amendment from Majority Leader Mitch McConnell (R-Ky.) that would have prevented President Obama from lifting sanctions on Iran until the country releases American prisoners and publicly recognizes Israel’s right to exist. Sixty votes were needed to move forward.

Under the Congressional Review Act, Thursday is the final day for Congress to approve a resolution stopping the nuclear deal, though some conservatives dispute that deadline.

With Democrats having held firm in the Senate, it appears the nuclear pact — negotiated by the United States and other world powers — will begin taking effect next month.

Sen. Jeff Flake (R-AZ) stuck with the GOP on the procedural vote, but announced that he would oppose the amendment if it came to a floor vote. Flake argued that the conditions are not serious enough to make a prerequisite for entering into a deal:

Sen. Jeff Flake (R-Ariz.) said that while he supports releasing hostages and Iran supporting Israel, “should a whole agreement be based on those two items? No.”

Both parties in this case made errors. Mitch McConnell would have done better to restrict the amendment to the fate of US hostages, whose disregard in these talks is indefensible. Recognition of Israel by the mullahs not only is a poison pill, but who’d believe them if they actually complied? Its inclusion allowed Democrats a political out for blocking it.

Strategically, though, the filibuster of this bill will be a disaster for Democrats. Why not have a floor vote? Obama would veto the bill, and Democrats have more than enough votes in both chambers to sustain it. Instead, they made themselves look weak and craven for no difference in outcome in protection of a President whose name is already all over this deal. It’s an incredibly dumb move, one that some Democrats will regret when they stand for re-election.

So, this leaves us with the big question: Does McConnell go nuclear on the filibuster in order to hold a floor vote that won’t prevent Iran from going nuclear in the end? Lindsey Graham defended the filibuster last night as a way for Republicans to keep Obama in check, but they have a majority that can keep bills from getting to the floor at all for the rest of Obama’s presidency. The real issue is that Republicans could be in the minority in 2017, and if Democrats keep the White House, it will get ugly without the 60-vote threshold. Is this the hill on which to fight — and if it’s not, as Graham argued last night, what is?