Sen. Lindsey Graham (R-S.C.) said on Nov. 30 that "the party needs to deliver" and pass its tax proposal. (Reuters)

The small business lobby. AARP. The medical community. More than half (52 percent) of Americans. Democrats in Congress. They all oppose a tax bill Senate Republicans are hurtling toward passing, as soon as Friday morning.

Republicans are racing to pass this tax bill despite the fact they don't know what will for sure be in it, nor how it would impact economic growth, nor how tax cuts directed mostly at the wealthy will play politically in next year's midterm elections.

So then, why the rush to pass it? Because, this: “Failure’s not an option,” said Sen. Lindsey O. Graham (R-S.C.) in the halls of Congress on Wednesday.

In other words, Republicans have come to the conclusion failure is worse than passing an unpopular tax bill. Way worse.

In the breath before, Graham had indicated he'll take pretty much anything that can remotely be called a tax bill: “Susan [Collins]’s got a concern, it’s a real legitimate concern. Ron Johnson’s got a concern. There’s a deficit concern. It’s like making a cocktail. If you’ve got to add more of this and less of that, I’m fine.”

Graham has been the most frank spokesman for how vital this tax bill is to the future of the Republican Party. Donors (who would benefit from this bill) would just stop giving to the party, he's warned. Republicans could lose their majorities in Congress, he and others have warned. Failures to pass it “will be the end of us as a party,” Graham told the New York Times at one point during this process.

Behind closed doors, Republicans in Congress agree. The common wisdom is they need to prove to donors and voters they can deliver on major campaign promises, the sooner the better.

Their concern may be warranted: Republicans control all levers of government in Washington, and yet they are coming up on one year without a major legislative accomplishment.

After Republicans' attempt to repeal Obamacare blew up in their face, donors and activists were aghast. Key conservatives —  even huge proponents of getting something, anything, done on health care — said it was time for Republicans to cut their losses and move on.

“This is an epic failure by congressional Republicans,” Tim Phillips, president of the conservative Koch network-funded group Americans for Prosperity, told me at the time. “But it’s time to pivot to tax reform. There’s no time to pout.”

What better way to move on from a failure than by passing something Republicans have spent years dreaming of doing? Especially if that something cuts middle-class taxes, which GOP operatives say would be the easiest bill to sell to an American public already skeptical of the job Republicans are doing controlling Washington.

“Politically, this is, always has been and always will be the most important issue,” Corry Bliss, head of the House GOP super PAC, the Congressional Leadership Fund, told The Fix this summer. “There's nothing more important than having a good-paying job and being able to provide for your family.”

So, Republicans have come to the conclusion something is better than nothing. That's really the driving force that could unify about 10 senators with competing concerns about the bill.

Here's the problem: Something could still cost Republicans. By all past standards of how major legislation gets made, they are rushing through this bill. It would make the biggest changes to the tax code in 30 years, and they don't have a lot of knowledge about what will happen next.

A key analysis by the Treasury Department the administration was expecting to use as evidence tax cuts at the top would rev the economy doesn't exist, the New York Times reported — lending credence to Democrats' and many mainstream economists' criticism that trickle-down economics doesn't work.

The Post's Fact Checker found that millions of Americans would pay higher taxes under the House's version of the GOP tax bill, while President Trump would benefit. A nonpartisan Congressional Budget Office report found poor people could see their taxes go up disproportionately under the Senate bill, while millions could be without health insurance. On Thursday afternoon, hours before votes were set to begin, the nonpartisan Joint Committee on Taxation found the Senate GOP bill would add $1 trillion to the deficit over a 10-year period, undercutting Republicans' arguments the bill would pay for itself.

In other words, this tax bill may not produce tax cuts for the middle class, that magic antidote to Republicans' failure to repeal Obamacare. There are a lot of other, unforeseen ways passing this tax bill could backfire politically for Republicans.

As Graham has voiced, there's one big reason it might pass anyway. Because of their past failures earlier this year, more failure is not an option.