After voting no seven times, Sen. Bill Cassidy, R-La., flipped and cast the deciding vote to advance a War Powers Resolution to rein in President Donald Trump’s war in Iran without authorization from Congress.

In a 50-47 vote, Cassidy joined fellow Republican Sens. Lisa Murkowski, R-Alaska, Susan Collins, R-Maine, and Rand Paul, R-Ky., who have previously supported the measure.

The vote marks the first time a War Powers Resolution on Trump’s Iran conflict has gained enough Republican support to advance to a floor debate.