The US Congress will have a say on a nuclear deal with Iran, under a new agreement reached with the White House.
President Barack Obama withdrew his opposition to a bipartisan bill that was unanimously passed through the Senate Foreign Relations Committee.
However, a Congressional No vote would not be binding and could be vetoed by Mr Obama.
An outline agreement on the future shape of Iran's nuclear programme was reached after marathon talks in April.
The US, Iran, and five other nations have set a deadline of 30 June to finalise a deal which would ease western sanctions in exchange for restrictions on Iran's nuclear programme.
Mr Obama agreed to sign the bill giving Congress the right to reject any forthcoming agreement with Iran.
Some Republicans have argued against the deal, saying Iran has received too many concessions.
They have always insisted they must have a say if any agreement means economic sanctions levied by Congress against Iran will be lifted.
The Israeli government, which has been fiercely critical of the deal with Iran, welcomed the agreement between Mr Obama and Congress.
White House spokesman Josh Earnest told reporters Mr Obama was not "particularly thrilled" with the outcome, but US media have pointed out that in the event of Congress rejecting a deal with Iran, Mr Obama would be able to use his presidential veto.
A two-thirds majority would then be needed for Congress to override the veto, which is viewed as unlikely.
The bill is now likely to clear both houses in the Republican-controlled Congress.
An earlier version of the bill had placed a 60-day halt to any plan by Mr Obama to lift sanctions on Iran.
But that review period has been reduced to 30 days.
Mr Obama will still be able to lift sanctions he himself imposed through executive action but he would be unable to ease those imposed by Congress.