On Tuesday, after this piece was published, Senate Republicans voted to move ahead and debate a repeal of Obamacare.

When future historians look back on American governance during the early decades of the twenty-first century, they will have many tragic and troublesome episodes to dwell on: the hanging chads of Palm Beach County, the invasion of Iraq, the passage of the Patriot Act, the Citizens United ruling, the Republican-controlled Senate’s refusal to grant Supreme Court nominee Merrick Garland a hearing, and the election of Donald Trump and his subsequent dumbing down and demeaning of the Presidency.

In this chronology, Tuesday’s health-care vote may also figure prominently: it could well be remembered as a historic abuse of the legislative process that the Founders spent so much time and energy constructing. Mitch McConnell, the Senate Majority Leader, is asking his colleagues to vote blindly and authorize consideration of a health-care-reform measure that could dramatically affect the welfare of tens of millions of Americans and shake up roughly a sixth of the U.S. economy.

Officially, McConnell is presenting a “motion to consider” the American Health Care Act of 2017, the bill that House Republicans passed in May. But the motion is really just a way to start debate on a Senate version of the reform measure—a version no one knows anything about. McConnell is refusing to say what the bill under consideration will look like. It could be the revised version of the Senate G.O.P.’s bill to repeal and replace Obamacare, which was widely thought to have perished early last week. Or it could be the repeal-only bill that was widely thought to have died late last week. Or it could be some other proposal, or many others, depending on how many senators are allowed to offer amendments and put forward their own pet plans.

McConnell is refusing to clarify what he intends to do because he and his colleagues in the Republican leadership believe that keeping things uncertain gives them the best chance of bringing on board some of the moderates and conservatives who scuttled their previous efforts. “We have no earthly idea what we will be voting on tomorrow other than that it’ll be moving to the House bill,” Senator Rand Paul, of Kentucky, who was one of those conservative dissidents, told Fox News on Monday. “But everybody knows it’s not really going to be the House bill.”

It is a ludicrous situation, and one that makes a mockery of the idea of the Senate as a highfalutin deliberative body. No major bill in recent history has been railroaded through the upper chamber in such a manner—conceived of and written in secret, and subject to no markups or committee hearings. If McConnell were to succeed in getting some sort of bill passed, it would be a travesty.

About the only thing that can be said for the lawmakers who brought things to this juncture is that they have been pretty open about their intentions. Indeed, they appear to wear their cynicism with pride. “We’re trying to maximize the number of votes,” Senator John Cornyn, the Majority Whip, told reporters on Monday. “What we’re trying to do is convince everybody that if they’d like to get a vote on their amendment, then they need to vote to proceed to the House bill.”

Senate Republicans, one would hope, haven’t descended so far that they would fall for this ruse, and Paul, for one, said that he wouldn’t. “I don’t think we should move to the bill with so many unknowns unless we’re going to be told what exactly we’re going to move to,” he said. Maine’s Susan Collins, one of the moderate Republican dissidents, also indicated that she was likely to vote against the motion. There were reports that Lisa Murkowski, of Alaska, was also going to vote no, but it later emerged that she was still undecided. If three Republican senators oppose the motion to proceed, it will fail. (The Republicans have a majority of just two.)

It was clear by early Tuesday that the G.O.P. leadership and the White House were making an effort to rally party loyalists and cajole the holdouts. McConnell was said to be willing to sweeten the pot for Republicans concerned about slashing Medicaid by adding back some two hundred billion dollars of spending for the federal program. Trump, meanwhile, spent some of Monday afternoon in West Virginia with the state’s junior senator, Shelley Moore Capito, whose vote will be crucial. And on Monday night, John McCain, stricken with brain cancer, gave the party leadership a boost by announcing that he would return to Washington for the health-care vote, in which he will almost certainly join the yeas.

Thankfully, the opponents of the Republican designs—which, let us not forget, could lead to at least twenty million Americans losing their health-insurance coverage, and countless others ending up with skimpier plans and astronomical deductibles—are also rallying. Democratic politicians and activists are fired up and engaged, as are organizations representing the people and interest groups that the reform would affect. On Monday night, A.A.R.P., which has about thirty-eight million members, called on all senators to vote against the motion to proceed.

But this looks like a close one—perilously close given that opinion polls show that a large majority of Americans prefer keeping Obamacare to adopting any of the Republicans plans. If the vote were to go McConnell’s way, it would be another sign that American democracy is failing.