Supporters of the international nuclear agreement with Iran moved within one vote of mustering enough support to protect the deal in the US Congress on September 1 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.
Altogether 31 Senate Democrats and two independents who vote with them now support the deal, a potential legacy foreign policy achievement for Democratic President Barack Obama.
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.
Both Casey and Coons said they had had serious questions about the agreement, but decided it was the best option for limiting Iran's nuclear program and preferable to the United States breaking from the other countries that signed the deal.
Supporters hope they will gather the 41 votes to block a disapproval resolution in the Senate and keep Obama from having to use his veto power. Congress has until Sept. 17 to pass a resolution.
Two Senate Democrats oppose the nuclear deal, along with an overwhelming majority of Republicans.
Several House Democrats announced support for the deal on September 1, including Adam Smith, the top Democrat on the House Armed Services Committee. More than 90 House members, all Democrats, now back the deal.
A two-thirds majority in each chamber is required to override a presidential veto and torpedo a pact in which Tehran agreed to curtail its nuclear program in exchange for relief from economic sanctions.
