Today Democratic Senator Barbara Mikulski committed her vote in support of the controversial Iran nuclear deal, bringing the total number of Senators backing the deal to 34—the magic number needed to ensure Democrats can sustain President Obama’s veto should Senators opposed to the deal bring forward a resolution of disapproval.

More from the AP:

Democratic Sen. Barbara Mikulski of Maryland became the crucial 34th vote in favor of the agreement.

“No deal is perfect, especially one negotiated with the Iranian regime,” Mikulski said in a statement. She called the accord “the best option available to block Iran from having a nuclear bomb. For these reasons, I will vote in favor of this deal.”

The backing from Mikulski, who is retiring next year, gives supporters the margin they need to uphold an Obama veto of a congressional resolution of disapproval if Republicans pass such a measure later this month.

And it spells failure for opponents of the international agreement who sought to foil it by turning Congress against it. Leading that effort were Israel and its allies in the U.S., who failed to get traction after spending millions of dollars trying.

Reaction on both sides, of course, exploded:

The battle isn’t over, though. Republicans and Democrats opposed to the deal still have the option of pushing a resolution through Congress expressing disapproval of the deal, a move that Republicans in Congress are confident could produce at least a pass, if not a veto-busting mandate.

Democrats don’t want it to go this far, though. They worry about the inevitable optic (as @RBpundit’s tweet—embedded above—points out) that will arise if President Obama is forced to use his pen as a sword, cutting his way through a Congressional mandate. For that reason, they plan on pushing forward with a plan to gain enough votes to block debate of any disapproving legislation entirely.