“This is a real mess, and it’s not a good mess.”

That’s how Utah Republican Sen. Orrin G. Hatch opened a news conference to respond to the plans of Senate Majority Leader Harry Reid, D-Nev., to use a procedural maneuver to effectively change the rules with a simple majority vote.

It’s just not clear yet what that mess might include if a last-ditch effort to defuse the ticking “nuclear option” fails when the Senate meets Monday night in a rare joint meeting in the Old Senate Chamber. There hasn’t been much talk about what tactics Republicans might employ in response if Reid follows through on his threat, but what’s certain is that the Senate rules still afford Minority Leader Mitch McConnell, R-Ky., many choices. Even at its most partisan times, the Senate runs on collegiality and unanimous consent. In a worst-case scenario, even things like fixing the hour for starting the next day’s session and approving the journal of the previous day’s work could be subject to debate.

Hatch demurred when ask about the chances of Republicans using a particularly obscure rule to block committee meetings or using similarly blunt instruments.

“We’ll have to wait and see,” Hatch said.

The “two-hour rule,” which says consent is required to hold meetings after the first two hours of a Senate session day, last surfaced in early May to delay the nomination of Thomas E. Perez to be Labor secretary, in an example of what Democrats say is obstruction at multiple levels in the process.

Perez is on the list of nominees on which Reid moved to limit debate July 11, and McConnell signaled the nominee would get the 60 votes to clear that hurdle under the traditional rules.

The same is true for several of the seven nominees on which Reid filed motions to invoke cloture, but not all of them. Consumer Financial Protection Bureau head Richard Cordray and a pair of National Labor Relations Board members serving after disputed recess appointments appeared as of Friday to have no path forward without the nuclear option. The constitutionality of the NLRB recess appointments will be decided by the Supreme Court next term, and Senate Republicans are among those involved in the case.

Apart from immediate questions about the mechanics of the change, there are an array of institutional questions, including what the minority’s immediate retaliation might be and why Reid isn’t going further.

Sen. Lamar Alexander warned that Reid’s move could cause some Republicans to abandon work on bipartisan legislation in favor of a permanent campaign.

“It will turn this into a national debate about who controls the new majority institution in our country because we’ll have a new one for the first time in 230 years,” Alexander said.

The Tennessee Republican has been at the center of conversations about finding a fix for federal student loan interest rates and working with a bipartisan group on nuclear waste policy legislation — two issues that could be expected to founder more if he pulls out as a result of the filibuster changes.

One problem for the GOP: The more it retaliates with procedural shenanigans of its own, the more likely Senate Democrats are to use the nuclear option to push through a more wholesale change in Senate procedures.

What About the Judges?

Oddly enough, the first real test of how the Senate would change if Reid pushes forward with his plan might come from the Democratic side.

The Senate Judiciary Committee is on track to endorse three nominations to the D.C. Circuit Court of Appeals. The second-highest court, as it is often known, also happens to be one of the federal appeals courts that ruled the NLRB recess appointments were invalid.

The NLRB case is part and parcel of the court’s work, handling a lot of complex material involving the federal government’s role.

Republicans, led by Judiciary ranking member Charles E. Grassley of Iowa, contend that the court’s workload is too light to merit filling any of the three judicial vacancies, an argument Democrats scoff at.

There’s of course another problem with the D.C. Circuit, one that Sen. Ted Cruz, R-Texas, made clear at a Wednesday confirmation hearing for Patricia Ann Millett. Cruz noted that he had long known Millett as a fellow member of the Supreme Court Bar, but he cited factors beyond her qualifications that may imperil her nomination.

“You find yourself in the midst of a broader battle, and a battle on issues, many of which are unconnected to your professional background and qualifications, about issues that sadly have consumed the D.C. Circuit for decades,” Cruz said. “There’s a lot of political games when it comes to judicial nominations.”

Cruz referred to a long-standing partisan standoff, citing the ill-fated nominations by President George W. Bush of Peter Keisler and Miguel Estrada to seats on the same circuit. In another irony, McConnell and the Senate GOP retained Estrada to represent them in the NLRB recess appointments case.

“There are workload issues that I think need to be discussed, but I think there is a broader context that is irrespective of your fine qualifications, but to be honest was irrespective of Miguel Estrada’s qualifications, or Peter Keisler’s, and so I think this is going to be a continued issue,” Cruz said. “I think partisan politics has driven this committee’s approach to the D.C. Circuit for over a decade.”

In essence, Cruz appeared to be saying that turnabout was fair play.

“They’ve already telegraphed that they’re going to block the next three judges on the D.C. Circuit. We thought that all along, but Grassley said it yesterday,” Sen. Charles E. Schumer said at a Democratic leadership news conference on Thursday.

“Given that no party has ever declined to fill the ninth slot on the court based on caseload, and given that the current caseload is quite high, I hope and expect my colleagues on the committee will proceed to evaluate each nominee on his or her own merits,” the New York Democrat said at the hearing a day earlier.

And yet, Reid has said his current procedural maneuvering won’t apply to the federal bench, making it unclear how the judicial wars will proceed.

“This is focused very concisely. Judges — we’ll do our best to get those done, we need the D.C. Circuit very much, we got one done,” Reid said. “But this is not about judges, it’s about presidential executive nominees.”

Outside groups haven’t made the distinction between executive and judicial confirmation slowdowns. A video montage released Friday by the liberal group Americans United for Change features, among others, Caitlin J. Halligan. Obama nominated Halligan to a seat on the very same court, but her nomination twice failed to achieve the 60 votes needed to get cloture and overcome a filibuster. More recently, the Senate overwhelmingly confirmed Sri Srinivasan to a seat on the same court, 97-0.

Humberto Sanchez contributed to this report.