Donald Trump, in Maine, just got through unloading on Mitt Romney in response to the speech that Romney gave earlier today, casting the Mittster as a loser who begged for his endorsement — “on his knees” — and choked in 2012, fumbling away a challenge to Barack Obama that should have been won. That’s nonsense — the fundamentals actually favored Obama’s reelection — but for Trump, it’s always about casting his foes as weaklings and supplicants.

But the Trump-versus-Romney battle is clearly becoming a major front in what is increasingly evolving into a full scale GOP civil war, one that will probably spread into policy arguments. So I wanted to highlight a particular moment from Romney’s speech today that I think could have some significance going forward. In blasting Trump as unfit for the presidency, Romney said this:

If Donald Trump’s plans were ever implemented, the country would sink into prolonged recession. A few examples. His proposed 35 percent tariff- like penalties would instigate a trade war and that would raise prices for consumers, kill our export jobs and lead entrepreneurs and businesses of all stripes to flee America.
His tax plan, in combination with his refusal to reform entitlements and honestly address spending, would balloon the deficit and the national debt. So even though Donald Trump has offered very few specific economic plans, what little he has said is enough to know that he would be very bad for American workers and for American families.

Donald Trump proposes a tax plan that, when taken in conjunction with his refusal to detail the cuts to spending that he would implement, would balloon the deficit. That sounds pretty irresponsible! And Romney’s absolutely right about this.

But this criticism can be applied to Ted Cruz’s tax plan and Marco Rubio’s tax plan, too. All three of their plans would cut taxes across the board, resulting in large windfalls going to the top earners and steep declines in revenues. According to a Tax Policy Center analysis of the candidates’ tax proposals:

— Ted Cruz’s proposed tax cuts would lead to a decline of $8.6 trillion in revenues over a decade, while giving the top quintile of taxpayers a 13.7 percent boost in after tax income.

— Marco Rubio’s proposed tax cuts would lead to a decline of $6.8 trillion in revenues over a decade, while giving the top quintile of taxpayers a 6.2 percent boost in after tax income.

— Donald Trump’s proposed tax cuts would lead to a decline of $9.5 trillion in revenues over a decade, while giving the top quintile of taxpayers a 9.7 percent boost in after tax income.

Trump’s plan would likely explode the deficit the most, but Cruz’s and Rubio’s plans would also probably balloon the deficit by a substantial amount. All three, of course, maintain that their tax plans would unleash such spectacular growth that their tax cuts would be paid for by the explosion in revenues that would result. But Romney doesn’t appear to find this argument mitigating, at least when it comes to Trump’s plan. And so, when Romney blasts Trump’s proposals for failing to detail how his tax cuts would be paid for by spending cuts, that criticism should be applicable to the other candidates, too. (Note that Romney didn’t refer to Trump’s “tax cuts“; he only referred to his “tax plan.”)

One other interesting thing worth noting: Romney faulted Trump’s plan for ballooning the deficit while “refusing to reform entitlements.” This is apparently a reference to Trump’s promise not to cut entitlements. Translating Romney’s argument, what he’s really doing is attacking Trump as irresponsible for promising deficit-busting tax cuts for the rich without proposing to pay for them by cutting social insurance for the elderly.

Trump’s plan is indeed mathematically absurd. But Romney’s line of criticism doesn’t exactly seem like great politics. And if logic and consistency matter at all, it should apply to any candidate who refrains from elaborating the specific spending cuts he would pursue to prevent his tax cuts from exploding the deficit — something, of course, that’s politically difficult to do.

Thank you, Mitt Romney, for affirming that all of the Republican candidates should detail how their tax cuts will be paid for!