Last October, dozens of House progressives were slapped down by the US foreign policy establishment for floating, in the words of one congressional staffer, “the softest trial balloon about diplomacy” to end the Ukraine war. The episode seemed to slam the door shut on even the mildest progressive dissent from White House policy on the war, with the nine months that followed defined largely by lockstep Democratic support for the administration’s wishes, with only a relatively small cohort of Republicans defying the president in the form of voting against further military aid.

But President Joe Biden’s decision earlier this month to approve the transfer of cluster munitions for use by Ukrainian forces may have opened that door a crack. Last night, in a failed 147-276 House vote to ban the provision of the notoriously child-maiming weapons, forty-nine Democrats and ninety-eight Republicans voted for an amendment to that end brought forward by Rep. Marjorie Taylor Greene (R-GA). Despite the roughly 2-1 margin against Greene’s measure, the vote marks one of the most significant congressional challenges to the Biden administration’s approach to the war since the Russian invasion last February, and is certainly the most substantial episode of progressive dissent from the White House on the matter.

The vote is doubly significant given the underhanded maneuvering that took place to kill its backing. The original National Defense Authorization Act amendment to block the White House’s cluster munitions transfer — one that Biden is embarking on using a loophole to get around an unambiguous legal ban on sending the deadly civilian-killing shells — was put forward by two Democrats, Reps. Sara Jacobs (D-CA) and Ilhan Omar (D-MN) and was accompanied by a letter from them and seventeen other House Democrats renouncing the move.