Ahead of the offensive, Democratic Sen. Tim Kaine of Virginia introduced a war powers resolution designed to limit the use of the U.S. armed forces against Iran without congressional approval.

Six days after the airstrikes, the Senate took up the measure — privileged resolutions reach the floor, whether the majority’s leadership likes it or not — and it was not subject to the 60-vote filibuster rule. In other words, all Kaine’s proposal needed was a simple majority.

He didn’t get one.

The 53-47 vote opposing the resolution fell mostly on party lines — with Sen. John Fetterman, D-Pa., and Sen. Rand Paul, R-Ky., as the only senators to break with their own sides.

At this point, the effort might appear moot. After all, the strikes already happened, and the White House has already effectively declared “mission accomplished.”....

What’s more, despite the recent chatter about Saturday’s mission being a “one-and-done” operation, the president himself continues to make clear that he’s prepared to launch additional strikes as he — and he alone — sees fit.

Ahead of the vote, The New Republic’s Greg Sargent argued that if the Senate rejected the resolution, it would “only embolden Trump at a time when he is clearly growing more unhinged, power-crazed, and deaf to outside voices.” Hours later, senators missed an opportunity to apply some checks and balances on a White House that needs to be checked and balanced.