By Patricia Zengerle and Susan Cornwell
WASHINGTON (Reuters) - Democrats said on Friday that they would have enough votes to ensure that the U.S.-led international nuclear deal with Iran survives review by Congress, despite influential Democratic Senator Chuck Schumer saying he would vote against it.
A spokesman for Senator Dick Durbin, who counts Democratic votes as the Senate's minority whip and who supports the deal, said Democrats were still confident they could rebuff Republican attempts to sink the agreement in a showdown next month.
"The momentum is behind this deal, as you've seen from Democrats coming out this week," spokesman Ben Marter said.
Schumer, New York's senior senator, announced late Thursday that he would oppose the nuclear pact between six world powers and Iran announced on July 14.
President Barack Obama is trying to win over enough of his fellow Democrats to block Republican efforts to pass a "resolution of disapproval" that could cripple the deal, which is designed to curb Tehran's nuclear program in exchange for lifting of economic sanctions.
Congress has until Sept. 17 to vote on such a measure. If it passes, as even many in Obama's administration believe, there would be 22 days for the president to decide on a veto and Congress to try to override it.
So far, at least 14 Senate Democrats and independents who vote with Democrats and about 34 House Democrats have announced they would back the deal. There are 46 members of the Democratic caucus in the 100-member Senate and 188 Democrats in the 435-member House.
Most Republicans have already said they are opposed, as have a handful of House Democrats.
Senator Kirsten Gillibrand, New York's junior senator, announced her support on Thursday, hours before the announcement by Schumer. Senator Tammy Baldwin of Wisconsin announced on Friday she approved.
WHITE HOUSE SHRUGS OFF SCHUMER
Obama spokesman Josh Earnest said the White House was "not particularly" concerned that the decision by Schumer, the third-ranking Senate Democrat, would encourage more opposition.
"We continue to be confident that the vast majority of Democrats in the United States Congress will make a decision based on their own conclusions and not on Senator Schumer's," Earnest said told reporters.
Representative Eliot Engel of New York, the top Democrat on the House Foreign Affairs Committee, had also said on Thursday he opposed the deal.
Democrats said neither Schumer nor Engel had been expected to be yes votes. Pressure on them and other Jewish lawmakers had grown as Israel's government, and some pro-Israel lobbying groups, said the agreement would open the way for Iran to get a nuclear weapon and threaten Israel's existence.
However, if either had backed the deal, it could have tipped the balance strongly in favor of approval, Democratic aides said.
Schumer said he would encourage fellow senators to oppose the agreement, and would vote to override a veto.
A source closely tracking the issue said before Schumer's decision, it appeared possible for Democrats to have mustered the 41 votes they needed to use procedural votes in the Senate to block the Republican vote to "disapprove" of the deal.
Now, the fight will more likely be about ensuring they can keep Republicans from mustering the two-thirds majorities in both chambers to override an expected veto of the Republican move by Obama.
Administration officials were blunt in their disappointment with Schumer, who had had multiple briefings by top Obama aides.
Schumer came to meetings with a list of questions, but "those questions were lifted straight from AIPAC" a senior U.S. official said, referring to the pro-Israel lobbying group. "He came into it with a certain mindset," the official said.
Schumer said he made his decision "without regard to pressure, politics or party."
An aide in the House, where Minority Leader Nancy Pelosi of California is a strong backer of the deal, said nothing this week had altered Pelosi's confidence that she had enough votes to sustain an Obama veto of a resolution of disapproval, if need be.
(Additional reporting by Doina Chiacu and Lindsay Dunsmuir; editing by David Storey and Grant McCool)