After months of failed votes, the US Senate finally advanced Democratic legislation to end Trump's illegal assault on Iran, thanks to a Republican who just lost a primary in which the president backed an opponent.

The Senate has advanced legislation that seeks to force President Donald Trump to withdraw from the Iran war.

The war with Iran has now blown past the 60-day requirement under the War Powers Act for the president to seek the authorization of Congress.

The bill had previously been shot down with a lack of Republican support, but Sen. Bill Cassidy's defection could be crucial.

Measure marks a rare rebuke of President Trump