By Patricia Zengerle
WASHINGTON (Reuters) - Supporters of the international agreement with Iran on its nuclear program 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.
Democratic Senators Bob Casey and Chris Coons, who have been known as Iran hard-liners, both said they backed the international 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 in Wilmington, 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 have said they would vote against the deal, along with the overwhelming majority of Republicans in the chamber.
Backers of the agreement will need 34 votes in the Senate to sustain Obama's veto if a Republican-sponsored resolution of disapproval passes both the Senate and House of Representatives.
Coons told students at the University of Delaware it was too difficult to predict how many members of the Senate would eventually back the agreement.
Under a law Obama signed in May, Congress has until Sept. 17 to pass such a resolution. If one were to pass both chambers, and if lawmakers overrode Obama's promised veto, the president would lose his ability to temporarily waive many of the U.S. sanctions imposed on Iran over its nuclear program.
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 oppose the pact, and push for a tougher agreement.
Casey said he had studied the agreement intensively and 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.
(Reporting by Patricia Zengerle; Editing by Dan Grebler)