Washington: After securing a surprisingly broad and detailed framework for a nuclear agreement with Iran, President Barack Obama must now subject his signature foreign policy pursuit to the gauntlet of partisan American politics.

A blueprint finalized Thursday after marathon negotiations in Switzerland did little to ease the standoff between Obama and some lawmakers over Congress’ role in a final accord. The president has vowed to veto legislation giving Congress the ability to approve or reject a deal, and he made a fresh appeal for lawmakers to give the US and its international partners space to hammer out a comprehensive agreement ahead of a June 30 deadline.

But Republican leaders reaffirmed their intent to vote on legislation giving Congress the last word. Republican Senator Bob Corker, chairman of the Foreign Relations Committee, said the panel will vote on such a measure when lawmakers return from a spring recess on April 14.

“The administration first should seek the input of the American people,” Corker said.

Some Democrats have backed Corker’s quest for a congressional vote on an Iran deal, raising the possibility that lawmakers could override a presidential veto. Senator Bob Menendez is among those who backs congressional action.

“If diplomats can negotiate for two years on this issue, then certainly Congress is entitled to a review period of an agreement that will fundamentally alter our relationship with Iran and the sanctions imposed by Congress,” Menendez said in a statement Thursday.

For Obama, achieving a nuclear deal with Iran would be a crowning foreign policy achievement and a validation of his pursuit of diplomacy. His overtures to Iran date back to his first presidential campaign in 2008, when he said he would be willing to talk with Tehran’s leaders without preconditions. As president, he has staked enormous political capital on the nuclear negotiations, including secretly approving backchannel talks with Iran largely without the knowledge of Congress and key allies.

Obama assured Americans on Saturday that a newly negotiated framework for a nuclear pact with Iran was a “good deal” as he sought public support for a diplomatic breakthrough.

“It’s a good deal, a deal that meets our core objectives, including strict limitations on Iran’s program and cutting off every pathway that Iran could take to develop a nuclear weapon,” Obama said in his weekly radio and Internet address, broadcast on Saturday.

“This deal denies Iran the plutonium necessary to build a bomb. It shuts down Iran’s path to a bomb using enriched uranium,” he said.

Obama completed calls to John Boehner, the Republican speaker of the House of Representatives, as well as House Democratic Leader Nancy Pelosi, Republican Senate Majority leader Mitch McConnell and Senate Democratic Leader Harry Reid, by Friday afternoon, the White House said.

Senior aides said Thursday that Obama has devoted more time to Iran in recent weeks than any other foreign policy issue, a striking acknowledgment given the upheaval in Yemen and US military engagement in Iraq and Syria.

With Congress in the midst of a two-week recess, the Obama administration has time to wage a campaign to get lawmakers to hold off on legislative action.

Senior administration officials said Obama is open to discussions about how Congress can play an oversight role, though they reiterated Obama’s opposition to any legislative action occurring while negotiators try to hammer out a final agreement ahead of a June 30 deadline. Officials also did not specify what kind of oversight role they envisioned for lawmakers.

Obama cautioned that it was still possible the parties won’t be able to find common ground as they hammer out tough technical details in the coming months. But he warned lawmakers that Congress must not be the body that derails a deal.

“If Congress kills this deal - not based on expert analysis, and without offering any reasonable alternative- then it’s the United States that will be blamed for the failure of diplomacy,” Obama said. “International unity will collapse, and the path to conflict will widen.”