Chief House tax-writer Kevin Brady is under the gun to make the tax bill’s iffy math somehow work. Photo: Andrew Harrer/Bloomberg via Getty Images

You might well figure congressional Republicans dream and scheme about tax-cut legislation all the time, night and day, weekends and holidays. It’s certainly that kind of obsessive preoccupation for them on the campaign trail.

Yet here we are, after having all year to prepare for 2017’s big barbecue of tax cuts, and on the very eve of the House GOP’s unveiling of its version of “tax reform,” the process has apparently devolved into sweaty madness, with a strong possibility the whole show will have to be delayed, according to Politico:

House Republicans are racing to finalize their tax reform proposal before its much-anticipated rollout Wednesday morning. But so many key details have yet to be finalized that some congressional sources worry the unveiling may have to be postponed …

[N]ot 24 hours before the bill’s big reveal, lawmakers had yet to settle on one of the most sensitive questions of all: How to pay for their proposed $5.5 trillion in tax cuts, since any major revenue-generator is certain to antagonize some powerful lobby or group of lawmakers who could defeat it.

As Josh Barro quips on Twitter: “Oh, that little detail!”

In their budget resolution Republicans gave themselves a ten-year total of $1.5 trillion in deficits they could burn up in tax cuts. But that was not remotely enough. And because they decided not to take the political heat associated with the big spending cuts they always proposed back when vetoes from President Obama made it all theoretical, the GOP now has to come up with revenue offsets to pay for at least that portion of the tax cuts that they can’t deem self-financed by the alleged economic growth they are unleashing.

Trial balloons have been lofted over the Capitol repeatedly, carrying possible revenue-raisers. Many have been shot down, beginning with a huge new “border adjustment tax” that importers and retailers stopped early on.

Yet the scrambling continues. In the last week House tax-writers appeared to cave on new limits for contributions to 401(k) retirement plans, and on a slower phase-in of corporate tax cuts. The White House noisily objected to both those ideas. And the near defeat of the budget resolution at the hands of House Republicans from high-tax states who objected to plans to kill the tax deduction for state and local taxes made that provision suddenly risky. So it’s all a moving target, which makes the average Republican member of Congress who is expected to be preparing lusty cheers for the unveiling tomorrow a mite nervous.

The vast majority of House Republicans have only an inkling of what’s in the legislation. The details, including the key question of who loses under the legislation, have been closely held by party leaders for months in order to keep lobbyists at bay ….

“[Speaker Paul Ryan] said the committee is ‘turning the dials’ and getting it to work. It’s all last minute stuff,” said Scott Hodge, president of Tax Foundation, as he left Ryan’s office after meeting with the speaker.

Yeah, they might need another day.