Republicans are set to make the audacious play of bypassing the Senate parliamentarian and moving forward with a budget resolution based on a scoring baseline set by Budget Committee Chair Lindsey Graham (R-S.C.) that would allow them to argue extending President Trump’s 2017 tax cuts won’t add to the deficit.

Senate Republicans are being careful to say they won’t “overrule” the parliamentarian — the Senate’s procedural umpire — but Democrats are already accusing Republicans of going “nuclear” by flouting the Senate’s rules and precedents.

“We think the law is very clear and ultimately the budget committee chairman makes that determination,” Senate Majority Leader John Thune (R-S.D.) told reporters Tuesday, arguing Graham has the authority to decide whether extending the Trump tax cuts would add to the deficit and need to be offset by big spending cuts or revenue-raising proposals.

The stakes are high as the outcome could determine the size of the tax relief package passed by the Republican-controlled Congress and whether Republicans are able to make the 2017 Tax Cuts and Jobs Act, the biggest legislative accomplishment of President Trump’s first term, permanent.

The biggest procedural question facing Trump’s agenda is whether Republicans can project their impact on future deficits by scoring them as “current policy.”

If extending the 2017 Trump tax cuts are judged as an extension of current policy, then they won’t be counted as adding to future deficits — at least, officially. That would allow Republicans to extend those tax cuts permanently, which is a top Senate GOP priority.

Senate Republicans are arguing that Graham, one of Trump’s biggest allies, will get to make that call.

And they contend the parliamentarian Elizabeth MacDonough doesn’t have a say in the matter, a controversial claim that’s getting strong pushback from Democrats.

“As the leader just said, the law seems to me to be very clear: It’s not a ruling by the parliamentarian. The budget chair gets to decide which baseline to use,” Senate Republican Whip John Barrasso (Wyo.) said.

“It happened when Democrats were in the majority. [Former Senate Budget Committee Chair] Kent Conrad [D-N.D.] years ago used that,” Barrasso added.

“I expect Chairman Graham is going to be the one to determine what the baseline is,” he said.

The parliamentarian is usually a towering figure in the Senate when the majority party tries to pass major legislation under a special process known as budget reconciliation, which allows them to avoid a filibuster.

Under regular order, controversial bills usually need 60 votes to pass the Senate, but under budget reconciliation, legislation can pass with a simple majority vote if it complies with certain rules that are interpreted by the parliamentarian.

Senate Democratic Leader Chuck Schumer (N.Y.) said Senate Republicans are gearing up to break the Senate’s rules and precedents by ignoring the parliamentarian.

“That would going nuclear, and it shows that Republicans are so hell-bent on giving these tax breaks to the billionaires that they’re willing to break any rules, norms and things they promised they wouldn’t do,” Schumer declared.  

The Senate’s so-called nuclear option is changing an important Senate rule or precedent by a simple majority vote.

Democrats say they plan to ask the parliamentarian to rule that Republicans must use a current law baseline for projecting the cost of extending the 2017 tax cuts.

“My sense is they’re going to need a ruling from the parliamentarian. I don’t think they can bypass the parliamentarian. I think they’re going to need the ruling,” said Sen. Tim Kaine (D-Va.), a member of the Senate Budget Committee. “That would be unheard of.”

He said if Republicans attempt to move forward without input from the parliamentarian, Democrats will try to get a ruling.

“We’ll probably make a parliamentary inquiry. Does Graham have the ability [to use a current policy baseline]? She’ll probably say no,” Kaine predicted. “They’re not able to do that without a vote.”

Republican and Democratic Budget Committee staff were supposed to meet with the Senate parliamentarian Tuesday to discuss the GOP plan to use a current policy baseline, but the meeting was canceled. 

A spokesperson for the Senate Budget Committee Democrats said it was “alarming to see — through press reports — that Republicans believe they don’t need to defend their effort to hide the true cost of their multi-trillion dollar giveaways that will add trillions of dollars to the national debt.”

The spokesperson called the current policy baseline a “budget fraud” that “upends decades of precedent.”

If the parliamentarian rules in favor of the Republicans and allows them to use a current policy baseline, then they can proceed as planned and advance their budget resolution on the floor.

If the parliamentarian rules against the current policy baseline, then Senate Republicans could decide the matter by a simple majority vote.

If Republicans vote to override the parliamentarian’s ruling, then they would set a new precedent for budget reconciliation.

They’re hoping to avoid a vote on the matter, but Democrats would force one anyway to underscore their argument that Republicans are violating norms and precedents.

Sen. Lisa Murkowski (R-Alaska) insisted that Republicans would not vote to overrule the parliamentarian.

“We’re not going to be doing that. We’re not going to be overruling the parliamentarian. They had a big, long conversation about it, and the way it’s going to be set up is it’s not overruling the parliamentarian,” she said after attending a closed-door Republican policy lunch.

She said the “rules allow” the budget committee chair to set the budget baseline.

“We would not be overruling the parliamentarian, we would be supporting the interpretation of the chairman,” she said.

Schumer said letting Graham dictate whether extending the Trump tax cuts adds to the deficit would be to run roughshod over Senate “norms.”

Under a current law baseline, extending the Trump tax cuts past 2025 would add an estimated $4.6 trillion to the deficit over the 10-year budget window and trillions of dollars more to the deficit beyond that window, according to the official budgetary score for the bill.

If the parliamentarian rules that Republicans must use a current law baseline, then the budget score for extending the Trump’s tax cut will show a huge deficit impact.

That would put pressure on them to come up with additional spending cuts to offset the cost.

And it would force them to sunset any extension of the 2017 Tax Cuts and Jobs Act to comply with the Byrd Rule.

That rule prohibits legislation passed under budget reconciliation from adding to the deficit — either by increasing spending or reducing revenue — in the years beyond the budget window.