Media playback is unsupported on your device Media caption The landmark Iran nuclear deal will stand

A Republican-backed measure to derail the Iran nuclear deal has been blocked by Democrats in the US Senate, securing a major foreign policy victory for President Barack Obama.

Mr Obama will now not have to veto any measures against the deal that puts limits on Iran's nuclear programme.

Republicans fell two votes short of the 60 needed to advance the resolution to a final vote.

Discussion on the deal continues in the House of Representatives.

"This vote is a victory for diplomacy for American national security, and for the safety and security of the world," said Mr Obama in a statement.

Senate Minority Leader Harry Reid called today's outcome "clear, decisive and final" and that efforts to derail the deal any longer are "simply a waste of time."

Analysis: Anthony Zurcher, BBC News, Washington

A vote not to vote isn't high political drama, but it's a sweet victory for Barack Obama nevertheless.

Despite a massive advertising and lobbying campaign by its opponents and near universal Republican opposition, the controversial Iran nuclear deal will survive.

During his first presidential campaign in 2008, then-Senator Obama pledged to talk with "our foes and friends" without preconditions.

Those efforts have reached fruition in normalised relations with Cuba and now, in the twilight of his presidency, a nuclear agreement with the Iranians. These - for better or worse, depending on whom you ask - will likely be viewed as the two key components of Mr Obama's foreign policy legacy.

The deal faced unanimous opposition from Republicans controlling Congress, Republicans running for president, Israel and its US lobbyists.

Starting next week, Mr Obama will be allowed to draw back US sanctions on Iran.

Republicans contend that the deal enriches Iran's power and brings it closer to building a bomb.

"This is a bad deal with decades-long consequences for the security of the American people and our allies," said House Speaker John Boehner. "We'll use every tool at our disposal to stop, slow and delay this agreement."