US Senate vote to curb Trump on Iran war fails

An amendment to restrain U.S. President Donald Trump's ability to wage war on Iran failed to clear the Senate Friday.

Under the measure Trump would have still been allowed to attack Iran in self-defense, but Republicans mounted sufficient opposition to it, saying it is unnecessary and could undermine efforts to check Iran.

The amendment needed 60 votes to clear the Senate, but over 40 senators voted in opposition in the 100-member chamber effectively scuttling it even though voting remains open.

It was to be added to the annual military spending bill, which cleared the Senate Thursday, if it had gained enough support.

Senate Majority Leader Mitch McConnell allowed the amendment to be tacked on retroactively -- a rarity in the federal legislature -- but voiced stern opposition to it.

"This amendment would be a radical departure from constitutional traditions and norms. It would weaken American deterrence and diplomacy at a time of heightened tensions caused by Iran's aggression in the Middle East. The Senate must defeat it," he said.

Trump and Iran's top officials have exchange bellicose rhetoric over the past couple of weeks as tensions have ratcheted higher.

The president on Tuesday starkly warned Iran that should it attack American targets the U.S. response would be overwhelming including the obliteration of at least some sites that would be hit in response.

Senator Tim Kaine, who along with Senator Tom Udall sponsored the amendment, urged Congress to support the measure before it was defeated saying lawmakers "should have the guts and the backbone to go on the record on any war before we order our troops into harm's way."