Three’s a crowd. Photo-Illustration: Daily Intelligencer; Photos: Getty Images

The Republican tax plan has a pair of major math problems. One is that the House bill cuts taxes on corporations and the rich so drastically, its (politically toxic) tax hikes on the upper-middle class — as well as other interest groups — are insufficient to make up for all the lost revenue. This is a problem because Republicans plan to pass their tax cuts through a special budget process that can only be used for legislation that doesn’t add to the deficit in the long term. The upshot of this: In order to make their current bill procedurally viable, Republicans are going to need to make it a lot less politically viable.

At present, the GOP plan already calls for revenue-generating measures that would weaken the real-estate market, hurt orphans, disadvantage the disabled, hobble research on cures for rare diseases, make it harder for veterans to find jobs, and raise taxes for around a quarter of middle-class families. These measures have already earned the bill the vocal opposition of the National Association of Realtors; National Federation of Independent Business (a small-business lobby); the National Association of Home Builders; Independent Sector (a lobby for charities); the National Farmers Union; and the American Institute of Architects, among others. To have any prayer of passing their desired tax cuts, Republicans are going to need to fight off all these enemies — while making many, many more.

Once they make the budget math work, Republicans encounter their second math problem: Assuming Democrats maintain uniform opposition — almost certainly a safe assumption, given how unpopular this a deficit-neutral version of this bill will be — Republicans can only afford to lose the votes of two GOP senators.

As of this writing, their current bill appears to have already lost three.

In recent weeks, John McCain reiterated his demand that Republicans pass their tax plan through a bipartisan process that honors the norms of regular order. McCain voted down his party’s Obamacare repeal bill precisely because it failed to meet this standard. And it will be impossible to pass the House plan — or anything close to it — through any but a rushed, secretive, partisan process.

On Monday, Susan Collins declared her opposition to repealing the tax on multimillion-dollar estates. The current bill includes such a repeal, and many House conservatives seem deeply attached to the provision for some mysterious reason.

And for months now, Bob Corker has insisted that he won’t vote for any tax plan that adds a penny to the debt — even during the first ten years after passage, when Republicans would be procedurally allowed to do so. The House bill has yet to be scored. But it looks like it would add at least $1.5 trillion to the debt over its first decade in operation.

Now, it is extremely possible that these legislators won’t be true to their word. Lord knows, Senate Republicans have rarely displayed the courage of their convictions over the past ten months.

But it’s also the case that this bill is only going to get uglier from here. Republicans still need to add a slew of politically poisonous tax hikes to this thing to make the budget math add up — and the Senate math already looks impossible.

None of this means that the GOP won’t be able to pass some kind of tax cut, eventually (perhaps, a much smaller, temporary one). But it’s hard to see how the Tax Cuts and Jobs Act ever becomes law.