A key Iran bill moved this week to being just one vote away from having the necessary Senate support to overcome a promised presidential veto. However, the Thursday release of a framework for a political agreement with Tehran has added enough new variables to the congressional debate that it could enable the White House to peel away some Democratic supporters of the legislation.

Virginia Democrat Mark Warner became the 66th senator to publicly support the legislation. But the elevation of Sen. Benjamin L. Cardin of Maryland to ranking member on the Senate Foreign Relations Committee is expected to complicate the prospects for both panel and chamber passage of the bill (S 625) in its present form.

“He strongly believes Congress has an oversight role,” said Cardin spokeswoman Sue Walitsky. “He wants to make sure the [bill] language is consistent” with the framework agreement laid out by the Obama administration.

The bill, sponsored by committee Chairman Bob Corker, R-Tenn., and Sen. Robert Menendez, D-N.J., would forbid President Barack Obama from lifting congressionally-imposed sanctions on Iran for two months while lawmakers reveal a final nuclear agreement. Such sanctions can then only be lifted if Congress passes a joint resolution approving the deal or does nothing. The legislation would also require regular reporting to Congress that Iran has not in any way supported terrorist acts against the United States, a provision that has drawn particular fire from critics for being outside the scope of the so-called “P-5+1” nuclear negotiations.

While Cardin supports the principle of congressional review, he said on Thursday he did not want to do anything that would undermine the president’s negotiating hand in nuclear talks.

The White House contends the legislation would harm prospects for reaching a final deal by June 30, by raising concerns in the minds of foreign negotiators that the United States cannot be relied on to fulfill its end of a bargain, i.e. providing sanctions relief. Under the terms of the deal, Iran would agree to drastically curtail its weapon-sensitive nuclear activities for 10 years. Some of those activities would be allowed to resume in the following next five years while others would be forbidden.

A Senate Democratic aide said the announcement of the political framework deal has inserted a number of new variables into the debate over passage of Corker-Menendez including on the timing of any votes. A committee vote had been scheduled for April 14.

“Throughout this process, the administration has said Congress has a role to play,” the staffer said. “It does seem like that role to play is now. With the framework of an agreed announcement in place, I suspect Congress will be more inclined to do something rather than nothing. The Corker bill is that something.”

Some outside experts, however, saw reduced prospects for passage due to the specifics that were announced on Thursday.

“I am pretty skeptical at this point that Congress will be able to push anything through with a veto-proof majority because I think the president has a pretty strong hand to play with this agreement,” said Ilan Goldenberg, a former Democratic staffer on Senate Foreign Relations, now with the Center for a New American Security. “If anything, you will probably see some Democrats move away.”

Jim Walsh, an expert on international security at the Massachusetts Institute of Technology agreed: “What we got announced yesterday was both more detailed than we expected and the details were more robust than expected from a nonproliferation standpoint.”