Congress will vote this month on a resolution to disapprove of the White House-backed nuclear deal struck with Iran by the U.S., Russia, China, Britain, France and Germany. The deal aims to limit Iran's nuclear program in exchange for hundreds of billions of dollars in relief from international sanctions.
Republicans who control both chambers of Congress are unanimously opposed to the deal. They need a majority in the 435-member House and 60 of 100 votes in the Senate to pass the disapproval resolution.
If the resolution does pass, President Barack Obama has pledged to veto it. At that point, opponents would need to muster two-thirds majorities in both the House and the Senate to override Obama's veto.
In the Senate, 38 senators have announced they support the deal. Forty-one votes would be required to filibuster the disapproval resolution in the first place and prevent it from passing.
A breakdown of where the 46 members of the Democratic caucus in the Senate stand: