NEW YORK – Education reformer Whitney Tilson is locking horns with U.S. Sen. Elizabeth Warren over President-elect Donald Trump’s decision to appoint Wall Street executives to head the Treasury and Commerce Department.

Tilson, who runs the hedge fund Kase Capital Management, is also a founder of Democrats for Education Reform and backer of Teach for America, a big fan of Warren, and vocal critic of Trump.

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Tilson told Bloomberg in late November that he was encouraged that Trump selected Goldman Sachs Group Inc. executive Steve Mnuchin as Treasury secretary, and investor Wilbur Ross to head the Commerce Department, because he worried the president-elect would take a more radical approach to curbing Wall Street abuses.

Tilson said he’s elated Trump may have angered his supporters by appointing insiders.

“I can take glee in that – I think Donald Trump conned them,” Tilson said. “I worried that he was going to do crazy things that would blow the system up. So the fact that he’s appointing people from within the system is a good thing.”

Tilson’s comments apparently ignited a fire under Warren, a consumer protection crusader Tilson greatly admired, and prompted her to pen a scathing attack on the hedge fund manager on her Facebook page.

“Billionaire hedge fund managers like Whitney Tilson are thrilled by Donald Trump’s economic team of Wall Street insiders,” Warren wrote in the post, quoting Tilson’s comments to Bloomberg.

“Tilson knows that, despite all the students and rhetoric, Donald Trump isn’t going to change the economic system – he’s going to tilt the playing field even further for those as the very top. (sic),” Warren continued before accusing Mnuchin of helping to cause the 2008 economic crisis.

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“If Trump gets his way, the next four years are going to be a bonanza for the Whitney Tilsons of the world – at the expense of the pain of everyone else,” she wrote.

Warren either did not read the entire Bloomberg article featuring Tilson, or simply ignored his other comments to the news site. She also apparently had no idea who she was targeting with her attack.

Tilson told Bloomberg that he’s “a fan of Dodd-Frank, I think banking should be boring.” He also said he fears “Wall Street returning to being a casino.”

In Tilson’s regular email to a very large list of education reformers, he explained why Warren’s comments struck him to the core. Tilson and his wife Susan have cheered Warren’s rise through political ranks since Susan was a student in one of Warren’s first bankruptcy classes at Harvard Law School in 1992. They also worked to support her senatorial campaign.

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The couple, who supported Clinton in the most recent election, even went as far as donating $1,000 to Clinton’s campaign to hear Warren speak at a Women Lawyer’s for Hillary event in September, Tilson wrote.

As Warren’s Facebook attack on Tilson racked up tens of thousands of likes and more than 1,000 comments, Susan penned a letter to the senator to explain why she’s essentially shooting herself in the foot.

She wrote:

First, you called him a “billionaire hedge fund manager,” which, I can assure you, is laughably far from the truth. Second, you clearly know nothing about him if you could ever characterize him as being “thrilled” about anything that Donald Trump is doing. In the months leading up to Trump’s election, Whitney did little else but use his bully pulpit (through Facebook and vast e-mail lists that he typically uses to share information about investing and education reform, which is his passion) to keep Trump from the Oval Office. The two of us, inspired by your talk at Skadden, even spent a day with friends in Bethlehem, PA, going door to door to register voters for the Clinton campaign. We believe that Donald Trump personifies greed, corruption, and ignorance, and we are deeply dismayed by the reality of his election to the presidency. We have three daughters on the cusp of adulthood, and this is not the world we imagined for them.

When Warren’s chief of staff replied that the senator would only remove the word “billionaire” from her Facebook rant against Tilson, and provide no other context or clarification, Tilson wrote back to air his grievances.

“Unfortunately, removing the word “billionaire” doesn’t fix the fact that Sen. Warren’s post still totally mischaracterizes what I said in the Bloomberg article and what I really believe,” Tilson wrote. “I hate Donald Trump and his toxic agenda with a passion, and fought with every fiber of my being to stop this racist madman/con man from becoming elected. Thus, the reason I expressed ‘glee’ at him screwing his supporters is that I’m angry with them for electing him so, emotionally, I’m delighted that they’re getting their just deserts.

“More importantly, practically speaking, as he continues to betray his supporters over and over again (coal jobs are NOT coming back; wait until they see what Andrew Puzder has in store for them, etc.), this will hopefully undermine his support, making it: a) more difficult for him to actually implement his agenda; and b) more likely that he’ll be a one-term President,” wrote Tilson, who invited Warren to call him to discuss the conflict further.

“Personally I feel betrayed,” Tilson told The New York Times on Monday. “In recent years, I’ve really stuck my neck out by very publicly supporting her, the C.F.P.B., and a tough regulatory approach to banks — none of which wins me many friends — and this is how she repays me.”

“By engaging in factually incorrect, ad hominem attacks, she’s getting down into the gutter with Trump. This is misguided and counterproductive,” he said.

Tomorrow, Times writer Andrew Sorkin is expected to publish a column criticizing Warren for her misplaced attack, Tilson told his followers.

“In spite of how badly Sen. Warren and/or her staff have handled this – I gave them every opportunity to fix this obvious mistake – I still support her (albeit with somewhat less enthusiasm) for two primary reasons,” Tilson wrote in his mass email. “1) I think she, far more than Donald Trump, is the true voice for the 60% of Americans whose real incomes today are lower than they were in 2000 (their anger/frustration is understandable; alas, their solution – electing an obvious madman/con man President – is likely, I believe, to make things worse, not better, for them…); and 2) I share her belief that banking should be boring, and that it’s insane to allow our financial system to be a highly leveraged casino that preys on average Americans.

“I wonder if she’ll be smart and gracious enough to sit down with Susan and me so we can put this behind us and figure out how to work together? I’m not holding my breath – I think her fame and power may be going to her head (though I hope I’m wrong – we Democrats need strong, SANE voices now more than ever)…”