WASHINGTON -- Senator Kirsten Gillibrand, Democrat of New York, has announced her intention to vote in favor of the Iran nuclear deal reached last month.The decision by Gillibrand to declare her support for the agreement, shortly before Congress' August recess, is a significant victory for the Obama administration, which needs 34 Democrats in the Senate to vote against a resolution of disapproval in order to sustain the president's veto. Both houses of Congress will hold that vote after a 60-day review period, ending in mid-September.Gillibrand represents a state with the largest Jewish population in the world outside of Israel, where political leaders across the political aisle roundly oppose the agreement. She is the fifteenth senator to publicly declare support for the deal, and the only New York lawmaker to do so: Four high-ranking Democrats in the House of Representatives from her state have said they will oppose it.Those congressmen are Grace Meng (D-NY 6th District), Kathleen Rice (D-NY 4th District) and, as of Tuesday, Nita Lowey (D-NY 17th District) and Steve Israel (D-NY 3rd District).Gillibrand's Senate colleague from the empire state, Chuck Schumer, remains undeclared. He is seen as a bellwether for the historic September vote, as he is the senior-most Jewish member of Congress and is expected to become leader of the Democratic caucus in the Senate after Harry Reid (D-Nevada) retires."I have decided to support this deal after closely reading the agreement, participating in multiple classified briefings, questioning Energy Secretary Ernest Moniz and other officials, consulting independent arms control experts, and talking with many constituents who both support and oppose this deal," Gillibrand stated in a post announcing her position."There are legitimate and serious concerns about this deal," she continued. But she said that the "imperfect" Joint Comprehensive Plan of Action, as it is formally known, is the only real option before the legislature."If we reject this deal, we do not have a viable alternative for preventing Iran from obtaining nuclear weapons," she said. "Without a deal, and without inspectors on the ground, we will be left in the dark as Iran resumes its pursuit of a nuclear weapon, with only months to go before it could enrich enough fissile material for a bomb. Without a deal, our options will be limited to insufficient unilateral sanctions, an invasion with yet another massive and costly land war in the Middle East, or a bombing campaign that offers nothing more than short-term gain under the best-case scenario."Senator Jeanne Shaheen (D-New Hampshire) also announced support for the JCPOA on Thursday as the "best available option."