Here's what happened.
The House and Senate were at an impasse on the night of Sept. 30. The House's then-most-recent ploy for extracting Obamacare concessions from Senate Democrats and the White House -- by eliminating health insurance subsidies for Congress members and their staffs -- had been rejected by the Senate. The 'clean' Senate spending bill was back in the House's court.
With less than two hours to midnight and shutdown, Speaker John Boehner's latest plan emerged. House Republicans would "insist" on their latest spending bill, including the anti-Obamacare provision, and request a conference with the Senate to resolve the two chambers' differences.
Under normal House rules, according to House Democrats, once that bill had been rejected again by the Senate, then any member of the House could have made a motion to vote on the Senate's bill. Such a motion would have been what is called "privileged" and entitled to a vote of the full House. At that point, Democrats say, they could have joined with moderate Republicans in approving the motion and then in passing the clean Senate bill, averting a shutdown.
But previously, House Republicans had made a small but hugely consequential move to block them from doing it.
Here's the rule in question:
When the stage of disagreement has been reached on a bill or resolution with House or Senate amendments, a motion to dispose of any amendment shall be privileged.
In other words, if the House and Senate are gridlocked as they were on the eve of the shutdown, any motion from any member to end that gridlock should be allowed to proceed. Like, for example, a motion to vote on the Senate bill. That's how House Democrats read it.
But the House Rules Committee voted the night of Sept. 30 to change that rule for this specific bill. They added language dictating that any motion "may be offered only by the majority Leader or his designee."
So unless House Majority Leader Eric Cantor (R-VA) wanted the Senate spending bill to come to the floor, it wasn't going to happen. And it didn't.