The process for moving any agreement to reopen the government and raise the debt ceiling could get tricky in the Senate this week.
If the House doesn't send over what's known as a "message" containing tax provisions, Senate leaders may have to resort to using a new, untested procedural tool.
Without unanimous consent, that process could still push the floor activity past the deadline, however.
Back in January, the Senate set up a new procedure for the 113th Congress that would allow Majority Leader Harry Reid to truncate the process of limiting debate on legislative business.
The Nevada Democrat has yet to deploy it though, because it could create new unpredictability for both Reid and his GOP counterpart, Minority Leader Mitch McConnell of Kentucky.
In short, the resolution created a way around the usual process which forces the Senate to spend days on breaking a filibuster of a motion to proceed. But it also requires Reid allows each party to offer two amendments. The agreement came about as part of the deal to avoid use of the "nuclear option" to change the Senate's rules with a simple majority vote. As summarized by CQ Roll Call in January:
Eliminates the right to filibuster a motion to proceed if the majority leader permits up to four amendment votes.a bit of an open question the agreement he hammers out with McConnell
If the majority leader wants to bring up a bill, he can get a vote to do so four hours after he files a motion to proceed.
At least two amendments from the majority and two from the minority must be allowed.
If one of the first four amendments isn't germane to the bill, it will be subject to a 60-vote threshold for passage.
That might move the process along more quickly, since Reid could take a House measure that's sitting on the calendar containing revenue language and move it through the chamber more quickly.
Republicans would get a window to secure votes on politically tricky issues such as an amendment drafted by Sen. David Vitter, R-La., and backed by Lindsey Graham, R-S.C., to kill employer health insurance contributions for members and staff under Obamacare.
Or maybe McConnell could offer up one of his own — like a delay of the individual mandate in the health care law or maybe even a measure blocking funding for the EPA's proposed rule on power plants that could prove costly back in Kentucky.
Of course, this could all be avoided by unanimous consent or if the House sends over an amendment to an existing bill with revenue language that's already ping-ponged between the chamber.
The revenue component is important since the emerging deal includes tax language, meaning it must originate in the House to avoid running afoul of the Constitution. The House also construes appropriations measures as needing to start on that side of the Capitol.
Sen. Bob Corker, R-Tenn., inferred that there isn't such a high-speed vehicle available in the Senate that would do away with the motion to proceed without making use of the bipartisan process.
"One of the things about the benefit of a House origination is it's a message. You can respond to a message immediately," Corker said.
Emily Pierce contributed to this report.