Former President Barack Obama is reportedly telling wealthy donors behind the scenes presidential candidate Sen. Elizabeth Warren (D-MA) is a formidable contender and could win the White House in 2020.

In recent months, Obama has talked up Warren to donors who are concerned by her constant targeting of Wall Street and the donor class, according to The Hill. Warren’s campaign has shunned taking contributions from high-dollar donors and Democrat bundlers, breaking with her past fundraising activities when she took money from donors for her 2018 Senate campaign.

Obama has reportedly said if she becomes the nominee to take on President Donald Trump, the party must come together to support her.

“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,” an unnamed Obama ally told The Hill. “I think he feels licensed to give an opinion on her because he’s ‘hired’ her.”

One Democrat donor said Obama views Warren as “very smart” and takes her progressive agenda seriously, adding, “he sees her running the campaign with the most depth.”

In addition to Warren, Obama has spoken warmly of his former vice president Joe Biden — who, despite his numerous gaffes, remains the race’s frontrunner. Obama infamously ruled against endorsing Biden’s 2020 bid and reportedly told another candidate that Biden lacks an “intimate bond” with voters, especially in Iowa, the first-in-the-nation caucus state.

While Obama has spoken highly of Warren and Biden, he has said he is not endorsing her or anyone else in the race until a nominee is chosen.

The report comes after Obama warned against adopting “purity tests” in the crowded Democrat primary. Speaking last month to roughly 100 donors in Los Altos Hills, California, the former president urged candidates to “chill out” and should be willing to support whoever becomes the nominee.

“We will not win just by increasing the turnout of the people who already agree with us completely on everything,” he said during a question and answer period, flanked by Democrat National Committee chair Tom Perez. “Which is why I am always suspicious of purity tests during elections. Because, you know what, the country is complicated.”

“We have a number of women candidates and we have one gay candidate. And those candidates are going to have barriers if they win the nomination, or they win the general election — just like I did,” he added. “You can overcome that resistance if the way you are framing these issues and messages indicate, ’Look, I’m part of an American tradition… of opening up opportunity.”