WASHINGTON (MarketWatch) — So now the economists are entering the political fray to give voters the benefit of their insightful analysis on the presidential candidates’ tax and spending plans.

Fortunately, the economics profession has so discredited itself with its failure to anticipate the financial crisis, to properly analyze or cope with the recession that followed, or to figure out a way to stimulate economic growth in its wake that their voices now are like that proverbial tree falling in an uninhabited forest — no one is listening.

But that has never stopped an economist from talking.

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So when a number of economic advisers from the Obama and Clinton administrations sent an open letter this week to Bernie Sanders dismissing his plans for single-payer health care and other economic policy measures as unrealistic, the public gave it the reception it deserved — they ignored it.

Four former chairs of the Council of Economic Advisers also directed their ire at an economics professor who ran numbers showing that Sanders’s policies would reduce unemployment to 3.8% (from about 5% now), raise median incomes an average $22,000, and boost gross domestic product growth to 5.3% a year (compared to 1.8% in 2015).

“ The intent of the unsupported and undocumented attacks on Sanders clearly is to reinforce the picture of a wild-eyed “democratic socialist” whose positions are unrealistic, making him unelectable. ”

These “extreme claims” by University of Massachusetts-Amherst Professor Gerald Friedman “cannot be supported by economic evidence,” wrote the former CEA chairs, including Alan Krueger, Austan Goolsbee and Christina Romer from the Obama administration and Laura Tyson from the Clinton administration.

“For many years, we have worked to make the Democratic Party the party of evidence-based economic policy,” these worthies sniffed in their letter. “Making such promises runs against our party’s best traditions of evidence-based policy making and undermines our reputation as the party of responsible arithmetic.”

A considered response to this objection might well be LMAO, but it is clearly another sign of the political establishment’s determination to marshal its resources against any insurgent candidate who defies the reigning conservative orthodoxy in economics.

It is true that the guns are out for Republican proposals as well. The Tax Policy Center — which bills itself as nonpartisan, but, who knows, may itself be “left-leaning” — blasted Ted Cruz’s flat tax plan, saying it would add $8.6 trillion to the federal deficit over 10 years while slashing taxes for the very wealthy.

But the three-paragraph letter to Sanders from the former CEA chairs ignores the supporting evidence in Friedman’s 53-page analysis — including 31 pages of appendices documenting his assumptions and sourcing his figures — and offers no proof for their claim beyond their bald assertion that Friedman is wrong.

Friedman, who obtained his undergraduate degree from Columbia and his doctorate from Harvard, joined the UMass faculty in 1984. He has told reporters he doesn’t work for the Sanders campaign and is supporting Hillary Clinton in the presidential contest.

But the cavalier dismissal of the Sanders plan without offering any evidence to support its rejection shows why the Vermont senator routinely directs his fury not only against “establishment politics,” but also against “establishment economics.”

And, as he sometimes adds on the campaign trail, the “establishment media.” The New York Times, for instance, which has editorially endorsed Clinton, ran an article this week headlined “Left-Leaning Economists Question Cost of Bernie Sanders’s Plans.”

The article, by reporter Jackie Calmes, consists largely of sweeping generalizations referring vaguely to “liberal-leaning economists,” “some experts,” and “progressive economists and business groups” without naming a whole lot of them.

Among the few named sources was, well, Austan Goolsbee, Barack Obama’s old buddy from the University of Chicago, who hitched his wagon to the Illinois senator’s star long enough to enjoy a whirlwind tour in Washington before returning to the groves of academe.

“The numbers don’t remotely add up,” Goolsbee told Calmes, though neither of them provided any evidence to support that assertion.

Other “left-leaning” economists named in the article are Jared Bernstein, who served as chief economist for Vice President Joe Biden and finds Friedman’s claims based on “wishful thinking,” and Paul Krugman, the Nobel Prize-winning economist who has invested so much in defending Obamacare over the past couple of years that he is reluctant to accept the single-payer concept.

For what it’s worth, there are some left-leaning economists who support Sanders. Thomas Piketty, the French economist whose 2014 best-seller “Capital in the Twenty-First Century” galvanized the discussion of inequality in this country, sees Sanders as a harbinger of a transformational change in the U.S. even if he falls short in this year’s effort of beating “the Clinton machine.”

“Sanders’s success today shows that much of America is tired of rising inequality and these so-called political changes,” Piketty wrote in an op-ed in the Guardian, referring to the conservative shift ushered in by Ronald Reagan and little changed by Bill Clinton or Barack Obama, “and intends to revive both a progressive agenda and the American tradition of egalitarianism.”

Hillary Clinton, he adds, “who fought to the left of Barack Obama in 2008 on topics such as health insurance, appears today as if she is defending the status quo, just another heiress of the Reagan-Clinton-Obama political regime.”

The intent of the unsupported and undocumented attacks on Sanders clearly is to reinforce the picture of a wild-eyed “democratic socialist” whose positions are unrealistic, making him unelectable.

But voters, to the extent they pay any attention at all to this sideshow, may decide that Sanders makes more sense than those orthodox economists who have guided us into the current mess of inequality, underemployment and rampant poverty.