Since the beginning of the 115th Congress, the Senate has operated in a procedural bubble, where Republicans can largely move nominations and legislation with simple majorities on the floor.

That has been the case for votes on the latest slate of Cabinet-level nominations that included confirmations of Montana Rep. Ryan Zinke to be Interior secretary, Ben Carson as Housing and Urban Development secretary and former Texas Gov. Rick Perry to be Energy secretary.

But the clock is ticking on how long Majority Leader Mitch McConnell can continue moving items through privileged procedures that only require Republican votes to carry the day.

McConnell began the year’s work on a fiscal 2017 budget resolution that does not have the force of law since it doesn’t require the president’s signature.

That measure was designed to fulfill a campaign promise by beginning the process of unwinding the 2010 health care law. It did that by including instructions for congressional committees to write legislation that affects the Obama-era overhaul and, like the budget resolution, would allow expedited consideration that only needs a simple majority for floor passage.

Senators have cast a few votes on less contentious bills that would have otherwise been subject to a Democratic filibuster, such as a bill to grant the Government Accountability Office access to certain sensitive information and a measure that was needed to allow Gen. James Mattis to serve as Defense secretary. He would have otherwise been ineligible, as he retired from the Marine Corps in 2013, which was within the seven-year cooling-off period required by law.

Democrats have been criticized for slowing the confirmation of the president’s nominees to round out his administration, but Republicans can push through almost all of them on their own, again with simple majority votes. But the procedural bubble the GOP has enjoyed will eventually pop when they must turn to legislation that is subject to a 60-vote threshold to limit debate. McConnell knows this, and the morning after President Donald Trump’s first address to a joint session of Congress last week, he asked Democrats to be a part of legislation that would require their cooperation.

“I know our Democratic friends have different ideas than us on many of these things. I know the far left is pressuring them to burn the place down because it can’t accept the results of last year’s election. But everyone knows that won’t get us anywhere at all,” the Kentucky Republican said on the floor.

Minority Leader Charles E. Schumer didn’t seem to be in the mood. In replying to McConnell’s floor remarks, the New York Democrat pushed back, revealing that the wounds from previous years, as well as the current atmosphere, continue to exert a pull on the chamber’s dynamics.

“I was listening to our Republican leader talking about compromise, not that he ever engaged in very much of it when he was leader last year, but compromise requires something to compromise over,” he said on the floor. “We have nothing from the administration — nothing on infrastructure, nothing on trade, nothing even on [the health care law]. … So you want to sit down and talk, let’s see what your plans are. Get your own act together before you point the fingers at Democrats.”

Of the 15 major Cabinet positions representing department heads, only two remain for Senate consideration: Sonny Perdue to be Agriculture secretary and Alexander Acosta for Labor secretary, along with other high-level slots like the director of national intelligence, for which former Indiana Sen. Dan Coats has been nominated, and the head of the Center for Medicare and Medicaid Services.

Those nominations and the budget reconciliation process can live comfortably in the Senate procedural bubble. After that, though, the House may provide the pin that pops it.

Congress is returning to work on the fiscal 2017 Defense appropriations bill that could fund Pentagon programs beyond the current spending bill, which expires at the end of April. Asked about progress on the conference report for that measure last Wednesday, Senate Appropriations Chairman Thad Cochran said, “We’re down to the lick-log.”

That bill is subject to filibuster, as are all appropriations bills, and would require a supermajority of 60 senators to limit debate for approval. It is too early to say what the final version of that spending bill will look like, but it is likely the first legislative reality check for the chamber.

“When we get to funding the government, obviously, it will be done on a bipartisan basis,” McConnell said last Tuesday. “It will be an opportunity for our Democratic friends to participate. They have chosen not to so far.”

Worth noting is that Senate Democrats have held the line in previous years to ensure parity between funding defense and domestic spending, and they’ve used procedural tactics like the filibuster to do so.

Jason Dick and John M. Donnelly contributed to this report.