President Barack Obama has signed legislation that gives Congress the power to review and potentially reject a nuclear deal with Iran.  

It's a central element of Obama's foreign policy. He signed the measure without ceremony Friday at the White House.  

Negotiators from the U.S., China, France, Russia, Great Britain and Germany are seeking a deal with Tehran by the end of June. Israel and some Persian Gulf nations worry Iran is simply delaying its nuclear ambitions to get economic sanctions lifted.  

The legislation would bar Obama from waiving congressional sanctions for at least 30 days while lawmakers examine any final deal. Congress would have to pass a resolution of disapproval to reject the deal, an action Obama likely would veto.  

Obama says he welcomes scrutiny of the negotiations.