Former President Barack Obama is not publicly endorsing any candidate, including, most notably, his former vice president. But according to inside sources, he is quietly vouching for one of the frontrunners behind closed doors: anti-Wall Street Massachusetts Sen. Elizabeth Warren.

Despite her repeated attacks on Wall Street, threats to extort “billionaire tears,” and disavowing big dollar fundraisers, Warren isn’t really the threat to the wealthy and Wall Street she appears to be, Obama has reportedly assured high-powered Democratic donors behind the scenes.

According to The Hill‘s Amie Parnes, in recent months, Obama “has gone to bat for Warren (Mass.) when speaking to donors reluctant to support her given her knocks on Wall Street and the wealthy.” If Warren should become the nominee, Obama urged the donors, “they must throw the entirety of their support behind her.”

“The former president has stopped short of an endorsement of Warren in these conversations and has emphasized that he is not endorsing in the Democratic race,” Parnes reports. “But he also has vouched for her credentials, making it clear in these private sessions that he deems her a capable candidate and potential president, sources say.”

“He’s asked all of the candidates who have sought his advice three questions: Is your family behind you? Why you? And why now? She checked the box for all,” said a “longtime Obama ally.”

Obama “feels licensed to give an opinion” about Warren, the source said, because he “hired” her in 2010 as a special adviser to the secretary of the Treasury, a role through which she helped install the much-maligned Consumer Financial Protection Bureau.