President Obama can now count on the votes of 33 senators who have expressed their support for the Iran nuclear deal, needing just one more Senate ally to ensure its approval in the US Congress, even if majority of lawmakers in the Republican-dominated Senate and House reject it.
Democratic Senators Bob Casey and Chris Coons, who used to be known as Iran hard-liners, appeared to have a change of heart as they expressed their support for the deal.
Among its 33 supporters, 31 are Senate Democrats while two are independents.
The Obama administration needs 34 votes in the Senate or 146 in the House of Representatives to sustain a presidential veto if the Republican-sponsored resolution of disapproval passes in both houses.
Casey and Coons said they had serious reservations about the Iran deal but decided that the deal reached between six world powers and Iran last July 14 was the best option to limit Iran's nuclear programme.
"I was never persuaded by arguments that we could ... renegotiate successfully and get a result," Casey said.
Coons said the deal will limit Iran's nuclear programme with the backing of the international community.
"I will support this agreement because it puts us on a known path of limiting Iran's nuclear programme for the next 15 years with the full support of the international community," Coons said in a speech at the University of Delaware.
Supporters of the Iran deal are hoping to get 41 votes to block the disapproval resolution in the Senate and prevent the President from using his veto power. The US Congress has until Sept. 17 to pass the resolution.
Two Senate Democrats have joined the Republicans in opposing the Iran deal.
In the House, several Democrats expressed their support for the deal Tuesday including Adam Smith. More than 90 House members, all Democrats, are backing the agreement.
A two-thirds majority in each chamber is needed to override Obama's veto on the Iran deal, which calls for Iran to curtail its nuclear programme in exchange for the lifting of economic sanctions.
A number of pro-Israel groups in the US echoed Israeli Prime Minister Benjamin Netanyahu's belief that the Iran deal will threaten Israel's existence.
