The procedural vote requiring 60 senators to move forward was initially scheduled for late Monday afternoon, but is now poised to happen on Tuesday morning. Reid moved the vote after Senate Minority Whip John Cornyn (R-TX) criticized him for the timing of it, saying many senators were absent.
It's not clear Democrats have the 60 votes needed to break a filibuster, but leaders believe they are close. The 55 Democrats are expected to be united in favor of the extension, and they have Sen. Dean Heller (R-NV) on board. So they need four more Republicans, and they're looking at five hopefuls.
Democrats believe Sen. Susan Collins (R-ME) may be a yes. They're also seeking to win over Republican Sens. Rob Portman (OH), Kelly Ayotte (NH), Lisa Murkowski (AK) and John McCain (AZ).
Cornyn suggested the vote would not succeed.
"I have no doubt as to what the outcome is going to be on this cloture," he said, "but it's purely a scheduling matter, I believe, and this ought to be postponed to a later time when we could have a real debate."