This is confusing, and if I haven't done a good enough job of unpacking it, mea culpa. But after it became clear that an Obamacare-defunding continuing resolution would be sent to the Senate, the Republicans' ability to protect that language depended on something that would never happen. And today, it didn't happen.
So: This afternoon, the Senate opened with a series of votes to tee up the cloture on the CR. Under normal Senate rules (Rule 22, if you want to check), after 60 votes are secured for cloture, amendments can be passed by a simple majority.
Knowing this, Cruz asked for unanimous consent on the House's CR. You read that right: He asked every senator to agree that the House's CR, the one that defunded Obamacare, was hereby approved. Every senator did not agree with this. Harry Reid objected. Strike one for Cruz.
Next, Cruz asked for unanimous consent for a 60-vote threshold on amendments to the CR. Once again, Reid objected. Strike two.
Cruz's failure, which was predestined, means that the next vote on the CR will be cloture on the House's CR as-is. Because Democrats need only 51 votes to amend it, Cruz et al. are attempting to convince Republicans to oppose cloture. They need to filibuster the bill to save the bill—although "save," in this context, means that the bill would hang in limbo. Not even Cruz's colleague from Texas is on board.
Left with no good options, Cruz just used the rest of his time today to insist that Democrats were now responsible for a shutdown. If only they had agreed to the House CR, he said, "there would be no government shutdown. A government shutdown would be taken off the table." He reminded Democrats that they'd agreed to 60-vote amendment thresholds during the gun debate, and that his own gun amendment would have succeeded until simple majority rules. (He did not mention that Manchin-Toomey also would have succeeded.) And then he exited, stage right.