During a speech in Indianapolis, Sept. 27, President Trump said the GOP tax plan is a "once-in-a-generation opportunity" to lower taxes on the middle class and businesses. (Bastien Inzaurralde/The Washington Post)

Republicans fanned out on the Sunday shows to defend their tax-cut plan. They didn’t help themselves, in part because they are saying two very different things. On one hand, they assure us that the middle class will benefit, the deficit won’t grow and this isn’t a boon to the rich. On the other hand, when pressed for details they claim it’s incomplete. Office of Management and Budget Director Mick Mulvaney on “Fox News Sunday” got caught in this contradiction when pressed to explain how this could be considered a middle-class tax cut when “those earning between $48,000 and $86,000 a year, they’ll get an average tax cut of $660 next year. Meanwhile, the top 1 percent, people making more than $730,000 a year, will get an average tax cut of almost $130,000 next year”:

You can’t look at the tax cut on a family until you realized how — how much better off they’re going to be in a growing economy. But beyond that, they had to make assumptions because we didn’t put any in the framework yet about where those particular tax rates kick in. They’re — there’s nothing in the document yet about that. Not because we’re hiding it, but because we’re working with Congress to try and establish where the different rates kick in.

In other words, he can assure us this is not a tax cut for the rich, but it doesn’t matter because the economy will grow — and no one can criticize an unfinished plan. So how then can they promise that … well, you see the problem.

The administration and congressional leaders continue to mislead in denying that their half-baked plan is a big fat tax cut for the rich. Treasury Secretary Steven Mnuchin took a beating on ABC’s “This Week” when he claimed this wasn’t a giveaway to the rich and President Trump wouldn’t benefit:

GEORGE STEPHANOPOULOS: You and your colleagues have said the wealthy will not get a tax code under the plan. … [But] the nonpartisan Tax Policy Center calculates that 80 percent of the benefits will flow to the top 1 percent. We’re going to show that chart right now.

Almost every group getting a tax cut, but the wealthiest getting the most.

That’s just a fact, isn’t it?

STEVEN MNUCHIN, TREASURY SECRETARY: George, first of all, it’s great to be with you this morning. And, no, that’s not a fact.

As we release the details of the plan, we’ll show the — all the different impacts to different people. And as the president has said all along, the changes to the income-tax system are meant to create middle-income tax cuts and also make corporate and business tax competitive so we can bring back tons and tons of jobs and capital to this country.

STEPHANOPOULOS: I know that’s the objective, but based on the evidence you’ve put out so far, all those cuts I just talked about, that will benefit the wealthiest the most.

MNUCHIN: Well, George, I just don’t think that’s the case. As we’ve talked about, changes in the top bracket are offset with elimination of almost every single type of deduction, other than charitable giving and the mortgage interest deduction.

And, you know, this has impact to different people in different states, but again, we’ll go through all the details as we go through the congressional process of the House and the Senate and we’ll show all the distributions.

And as it relates to pass-throughs, this is about creating jobs. A huge component of the businesses in this country are pass-throughs and we want to make sure they have the necessary tax relief to go out and hire more workers and invest more capital.

STEPHANOPOULOS: You know, secretary, I just don’t understand how you can say, based on everything you’ve put out so far, that it’s not a tax cut for the wealthy. Even the vice president has said these are across-the-board tax cuts. The wealthy pay most of the taxes. They are getting tax cuts there. They are going to get benefits.

MNUCHIN: Well, George, in the high-tax states, the impact is about 5 or 6 percent. So if we cut the rate down to 35 percent, that’s actually an increase for the wealthy in the high-tax states. And as we’ve said, we’re considering what we do, if there is a need for a fourth bracket, to create more relief.

So this will all continue to go through the congressional process.

STEPHANOPOULOS: But eliminating the estate tax will only go to the wealthiest Americans, those that have estates greater than $11 million.

MNUCHIN: Well, you are correct in that sense. And, again, we’ve been talking about the income-tax system. As it relates to estate tax, you know, the death tax, we believe that people get taxed once and not twice. And that will enable them to keep lots of family businesses passed along.

But the estate tax, you are correct. The majority of the estate tax is paid by the wealthy. So we’re focused on changes to the income-tax system.

STEPHANOPOULOS: But you’ve proposed to eliminate the estate tax.

Around and around they went. Mnuchin insisted a bill with provisions aimed only at the rich wouldn’t benefit the rich and that we’d need to take Trump’s word for it that he wouldn’t benefit. At the end, he too was reduced to claiming no one could challenge his assertions because the bill was incomplete. Stephanopoulos pointed out that Trump would have gotten an enormous benefit from the 25 percent rate for pass-through companies:

MNUCHIN: George, as we’ve said all along, as we change the pass-through rate, it’s very, very important that we have guard rails around those rules so exactly as you’ve said, this isn’t about creating a tax cut for the rich.

So we spent a lot of time with the staff at the House and Senate. We’re continuing to work on those rules. But we’re going to make sure that that’s not a way that the rich can use to pay lower taxes than they should, whether it’s the president or anyone else.

STEPHANOPOULOS: Well, but based on last year’s form, he would have gotten that benefit.

So how are Americans going to know whether or not the president gets this benefit if he doesn’t release his tax returns?

MNUCHIN: George, that’s just not fair, because, again, we haven’t published the rules as to what’s going to apply to the pass-through rate. So you’re making certain assumptions that I don’t think are correct.

STEPHANOPOULOS: I wouldn’t need to make the assumptions if we had the president’s tax returns. And I guess that’s the question. The president himself has said publicly he’s not going to get a benefit from this tax plan.

My question to you is, how are the American people going to know that if he’s not, releasing his tax returns? …

MNUCHIN: Well, I don’t know how the Tax Policy Center can publish those figures, since they don’t have all the details, including the brackets. People like the Tax Foundation and others have waited, which I think is responsible, when we release all the information …

STEPHANOPOULOS: But that’s on you. … if you haven’t released the details?

MNUCHIN: Yes, well, we’re working with the House and Senate. It’s going through committees. And those details are going to be released. And we’ve said that continuously.

It was a shabby performance from a treasury secretary who has already blown his credibility. Perhaps the administration should stop misrepresenting what it has, finish its homework and subject itself to independent scoring. Better yet, the administration should go back to the drawing board and come up with something that isn’t a huge gift to millionaires and billionaires.