The Senate voted to advance a bill curbing President Donald Trump's Iran war powers with the surprise support of Sen. Bill Cassidy (R-LA).According to The Associated Press, "Since Trump ordered the attack on Iran at the end of February, Democrats have forced repeated votes on war powers resolutions that would require him to either gain congressional approval for the war or withdraw troops. Republicans had been able to muster the votes to reject those proposals, but Louisiana Sen. Bill Cassidy — fresh off a primary election loss in which Trump endorsed his opponent — switched sides to deliver a crucial vote to advance the legislation."The vote, which passed 50-47, is purely procedural, advancing the bill to the next stage. Sens. Lisa Murkowski (R-AK), Susan Collins (R-ME), and Rand Paul (R-KY) also voted with all Democrats to advance it.Cassidy, who has been in Trump's sights ever since he voted to impeach him after Jan. 6, came in third in a primary featuring Rep. Julia Letlow and Louisiana Treasurer John Fleming. The latter two will advance to a second round.