Billionaire Tom Steyer has resigned from the board of a think tank run by allies of Bill and Hillary Clinton, CNBC has learned.

Neera Tanden, the CEO of the Center for American Progress (CAP) confirmed to CNBC that Steyer stepped down as a director of the organization's board when he decided to run for president.

Tanden was an aide to former President Bill Clinton and became policy director for Hillary Clinton's 2008 run for president. She was an informal advisor to Hillary Clinton during her 2016 campaign to win the White House. She also served in President Barack Obama's administration.

Steyer informed the board of his resignation in a letter dated July 9. "I hereby tender my resignation as a Director of the Center for American Progress effective Tuesday July 9th, 2019," he wrote.

He announced his entrance into the 2020 race on that same day. He is dedicated to spending $100 million of his own money while on the campaign trail but has yet to qualify for the primary debate in September. Steyer has been a CAP board member since at least 2010, according to 990 tax returns.

The decision by the the Democratic megadonor-turned-presidential candidate to step down comes as he has been distancing himself from outside entities that could be seen as giving his campaign an advantage.

Last month, he also walked away from leading NextGen America, which helped Democrats retake the House in the 2018 midterms, and Need to Impeach, a group that has been calling on congress to begin impeachment proceedings against President Donald Trump.

A spokeswoman for the Steyer campaign, Karla Hudson, noted that the former hedge fund manager's family office, Fahr LLC, will not be playing any role in the campaign. She claimed that Steyer is on track to qualify for the next primary debate in September but provided no details. Hudson later confirmed Steyer's decision to step down from CAP's board.

Candidates trying to make the third debate in Houston must get at least 130,000 contributions from individual donors and hit above 2 percent in four eligible polls by August 28.

The Center for American Progress calls itself a nonpartisan progressive policy institute "that is dedicated to improving the lives of all Americans, through bold, progressive ideas, as well as strong leadership and concerted action," its website reads.

Other members of the board include former Clinton campaign chairman John Podesta, former hedge fund executive Eric Mindich, Democratic donor Donald Sussman and businessman Glen Hutchins, who sits on the board of the Federal Reserve Bank of New York.

The groups most recent public tax return shows that CAP in 2017 spent $19 million on policy research programs involving a wide variety of progressive causes such as health care, immigration, open government, poverty and the environment.

CAP was embroiled in controversy in April when its news organization, ThinkProgress, took on progressive 2020 contender Senator Bernie Sanders. The group published an article and video that claimed that Sanders was trying to hide his status as a millionaire.

Sanders called out CAP and its affiliated group, Center for American Progress Action Fund, in a letter sent days after the article he described as a smear was published.

"The Center for American Progress is using its resources to smear Senator Booker, Senator Warren, and myself, among others. This is hardly the way to build party unity, or to win a general election," he said at the time.

Tanden distanced CAP from the ThinkProgress article, noting it was "overly harsh" and that it doesn't reflect who they are as an organization.

Since then, CAP has reportedly started the process of putting the news organization up for sale.