Donald Trump, left, and former House speaker Newt Gingrich at a campaign rally in Cincinnati. (John Minchillo/Associated Press)
Opinion writer

Even some of Donald Trump’s most high-profile supporters don’t believe the snake oil that he is peddling on economics. In a rare moment of honesty, Newt Gingrich let on that Trump’s tax and budget plans are nonsense. Asked by “Fox News Sunday” host Chris Wallace whether Trump’s plan to “cut taxes $9.5 trillion over the next decade, most of it going to top earners, and add[ing] $11.2 trillion to the debt with unspecified spending cuts” adds up, Gingrich said, “Of course not.” In what must be a new low in political cynicism, Gingrich argues that no politician’s numbers add up.

But shouldn’t they, you know, try? What’s the point of presenting oneself as a sincere conservative, as Gingrich has for decades while making a mint, if it’s all lies? This is precisely the political nihilism that has given the party and the country Donald Trump. Facts don’t matter. The truth is irrelevant. In short, it’s all a scam.

Gingrich has been among the most cynical and intellectually dishonest (against stiff competition, mind you) of Trump hangers-on. He’ll argue against any and all positions (e.g. NATO support, free trade) that he once advocated. It would be hysterically funny if not so indicative of the soullessness afflicting so many self-appointed GOP “stars.”

It’s not just Gingrich who is willing to prevaricate on policy. Trump was ridiculed for rolling out a panel of economic advisers (do they ever meet with him, really?) that is, as The Post put it, “heavy on investing and corporate experience but includes no women — and six men named Steve.” Even worse, the price of admission seems to be a major donation to Trump. (Politico reports that “five are major donors whose families combined to give Trump’s campaign and his joint fundraising account with the Republican Party more than $2 million. Two more have been pursued for campaign contributions.”) It’ s the ultimate pay-to-play scheme. (To his credit, Carl Icahn, whom Trump has said would be a trade negotiator, is not on the panel.)

Moreover, a number of them don’t believe the claptrap that Trump is selling; they are just going along for the ride.

Stephen Moore, the founder of the Club for Growth and a former opinion columnist for the Wall Street Journal who is now with the conservative (at least it’s supposed to be) Heritage Foundation, believes in free trade. In March, Moore wrote:

Donald Trump keeps scoring victories in Republican primaries with his protectionist threat of a 45 percent tariff imposed on China. Meanwhile on the Democratic side of the aisle, Hillary Clinton and especially Bernie Sanders keep bashing free trade for shrinking the middle class.

These attacks against international trade are mostly spurious because American workers engaged in export industries get paid 15 to 20 percent on average more than workers in domestic-only jobs. We export high-value added products and import low-cost consumer items.

Dan Mitchell of the Cato Institute notes that free trade has become the convenient political scapegoat for voter frustration with a stagnant economy.

So naturally he signs up with someone who has made irrational and wrongheaded arguments about trade the center of his campaign.

Moore has long touted the benefits of legal immigration. He has co-authored a book on it. (“First, immigrants may expand the demand for goods and services through their consumption. Second, immigrants may contribute to output through the investment of savings they bring with them. Third, immigrants have high rates of entrepreneurship, which may lead to the creation of new jobs for U.S. workers. Fourth, immigrants may fill vital niches in the low and high skilled ends of the labor market, thus creating subsidiary job opportunities for Americans. Fifth, immigrants may contribute to economies of scale in production and the growth of markets.”) Like virtually every free-market economist, Moore has debunked the very lies about immigration Trump now puts at the center of his campaign.

The one thing Moore does believe in — and which Trump says he supports — is a decidedly un-populist tax plan that gives huge breaks to rich people like Trump and leaves a giant puddle of red ink behind. Moore also has spent decades inveighing against pols who ignore runaway entitlement reform. Naturally, then, he signs up with Trump, who says no reform is needed whatsoever.

What accounts for such jaw-dropping hypocrisy? Well, advisers always tell themselves that they can push the candidate in the right direction. It’s almost always unrealistic; in Trump’s case, it’s self-delusion. Some advisers justify climbing on board — like party hacks — because the other candidate is worse. This, however, is unprincipled political maneuvering; it is not what policy experts and public servants are supposed to do. They are not obligated to lend their policy stamp of approval to a deeply flawed candidate — unless they have images of White House offices dancing in their heads.

This is the great unfolding tragedy of Trump. Once-respected figures on the right sacrifice intellectual credibility to shill for someone with no interest in policy and entirely devoid of the skills and temperament to be president. The number of people willing to jump on the Trump train wreck for the sake of careers, fame and wealth is as breathtaking as it is stupid (Trump’s not getting elected, folks) in a party in which the past dozen years have been spent fighting over who is more politically pure. I guess the real answer is the ones least committed to conservatism are the ones advocating the loudest for Trump.