In a rare bipartisan accord, the Senate overwhelmingly approved a compromise bill Thursday that would give Congress power to review any nuclear deal with Iran.
The measure passed, 98 to 1, and is likely to clear the House as early as next week, providing an outlet for lawmakers determined to have a say in an emerging deal between six international powers and Iran.
The nearly unanimous Senate vote came after President Obama threatened to veto proposals that would have given Congress a more assertive role or that would have added fresh demands to the ongoing negotiations.
The final bill, which the White House embraced, contained no such requirements.
Because of the prolonged controversy, even the bill's sponsors were surprised when only freshman Sen. Tom Cotton (R-Ark.) cast a no vote. Sens. Marco Rubio of Florida, Ted Cruz of Texas and Rand Paul of Kentucky — all candidates for the Republican presidential nomination — voted in favor of the bill.
Cotton had challenged Republican leaders last week by bringing to the floor two amendments that he said would toughen the bill. Critics said the provisions would doom the bill and thus cut Congress out of any role.
Thursday's lopsided tally came minutes after the Senate voted 93 to 6 to cut off further debate on the dozens of amendments that Republicans had offered.
The bill, sponsored by Sens. Bob Corker (R-Tenn.) and Benjamin L. Cardin (D-Md.), would give Congress "the right to vote for or against any change in the status quo when it comes to Iran," said Sen. John Cornyn (R-Texas), moments after passage.
The White House also portrayed the bill as a victory.
Bernadette Meehan, spokeswoman for the National Security Council, called it "the kind of reasonable and acceptable compromise that the president would be willing to sign."
She urged the House to "similarly protect this compromise bill, which constitutes a straightforward, fair process for Congress to be able to evaluate a final comprehensive deal."
Iran is negotiating with the United States and five other world powers — Britain, France, Russia, China and Germany — in an effort to meet a June 30 deadline to produce a comprehensive agreement that would ease economic sanctions if Tehran accepts restrictions intended to prevent it from obtaining a nuclear weapon.
The Senate bill would give Congress at least 30 days to deliberate over any final deal and set up a procedure for lawmakers to vote to register their support or disapproval.
During that period, the Obama administration would be barred from suspending any congressionally imposed sanctions on Iran.
It is unclear whether critics of a deal with Iran could rally enough congressional support to block an international agreement that the administration has helped negotiate.
Opponents would need 67 senators to override an expected presidential veto.
Some senior Republican lawmakers, and some U.S. allies, say they doubt congressional critics could stop a deal.
The measure won backing from many Democratic lawmakers who wanted Congress to have a say on the issue and who decided the bill didn't represent a serious threat to nuclear diplomacy.
Some Democrats said the measure doesn't give members of Congress any leverage over the Iran deal that they didn't already have.
Obama, who initially opposed congressional involvement as an infringement of his authority to conduct foreign affairs, shifted ground last month and said he could accept it. The bill had passed the Senate Foreign Relations Committee, 19 to 0.
Conservative critics sought last week to add a slew of amendments that threatened to derail the bill.
Rubio sought to require Iran to recognize Israel's right to exist, for example, an issue that was never part of the negotiations.
And on Thursday, Sen. David Vitter (R-La.) used procedural moves to stall the bill, which had been on the Senate floor for two weeks.
But almost all senators ultimately voted for the measure, they said, because of their desire to give Congress a say.
House Speaker John A. Boehner (R-Ohio) said he looked forward to the bill's passage in the House "to hold President Obama's administration accountable."
Congressional skeptics are expected in the coming weeks to bore in on the perceived weaknesses of a potential nuclear deal.
Corker said he was concerned that inspectors at the United Nations' nuclear watchdog, the International Atomic Energy Agency, might not have enough authority to determine whether Iran was complying with any agreement.
"One of the biggest challenges, to me, is going to be the inspections," he said.
But 150 mostly Democratic House supporters of the diplomacy registered their backing in a letter to Obama.
The letter's chief sponsors were Reps. Jan Schakowsky (D-Ill.), Lloyd Doggett (D-Texas) and David E. Price (D-N.C.).
Until now, most lawmakers have been cautious in registering support for the U.S. negotiations with Iran, saying they would first need to see the details of any deal.