By Patricia Zengerle
WASHINGTON (Reuters) - Supporters of the international nuclear agreement with Iran moved within one vote of mustering enough support to protect the deal in the U.S. Congress on Tuesday when two more Democratic senators said they would support the pact.
Senators Bob Casey and Chris Coons, known as Iran hard-liners, both said they backed the agreement announced on July 14 between the United States, five other world powers and Tehran.
"I will support this agreement because it puts us on a known path of limiting Iran's nuclear program for the next 15 years with the full support of the international community," Coons said in a speech at the University of Delaware.
Their support means that 33 members of the Senate, 31 Democrats and two independents who vote with them, now support the deal, seen as a potential legacy foreign policy achievement for Democratic President Barack Obama.
Two Senate Democrats oppose the pact, along with the overwhelming majority of Republicans in the chamber.
Backers will need 34 votes in the Senate or 146 in the House of Representatives to sustain Obama's veto if a Republican-sponsored resolution of disapproval passes both chambers.
Growing support has raised hopes that deal supporters might gather the 41 votes to use a procedural motion to block a disapproval resolution in the Senate and keep Obama from having to use his veto power.
At least three House Democrats also announced support for the deal on Tuesday, including Adam Smith, the top Democrat on the House Armed Services Committee. A total of 90 House members, all Democrats, now back the deal.
Congress has until Sept. 17 to vote on a resolution. If it passes both chambers, and lawmakers overrode Obama's veto, the president would lose his ability to temporarily waive many U.S. sanctions on Iran.
That could torpedo the agreement, in which Iran agreed to curtail its nuclear program in exchange for relief from crippling economic sanctions.
Among other concerns, opponents of the deal say it gives up too much to Tehran and does not include strong enough inspections of Iran's nuclear facilities. They say the United States should push for a tougher deal.
Casey said he had studied the agreement intensively. He issued a lengthy analysis explaining his decision.
"It places strict limitations on Iran's nuclear program, requires robust monitoring and verification measures, and grants relief only from nuclear sanctions in exchange for verified actions on Iran's part," he said.