Mike Bloomberg, former mayor of New York City, speaks to media after touring the Wind Technology program at Des Moines Area Community College in Ankeny, Iowa, December 4, 2018.

With Mike Bloomberg officially entering the 2020 Democratic presidential race, Bloomberg News will refrain from investigating him and his Democratic rivals, according to a memo sent to editorial and research staff obtained by CNBC.

"We will continue our tradition of not investigating Mike (and his family and foundation ) and we will extend the same policy to his rivals in the Democratic primaries. We cannot treat Mike's democratic competitors differently from him," Editor-in-Chief John Micklethwait said in the memo, which was confirmed by a spokesperson.

Mike Bloomberg is founder and 89% shareholder in Bloomberg LP, a financial software company that owns Bloomberg News

While the billionaire former New York mayor is running for president, Bloomberg News will publish or summarize investigative work into Bloomberg and the other Democratic candidates if made by "credible journalistic institutions," said Micklethwait.



Bloomberg News will cover the campaigns of the Democratic candidates, including Bloomberg's. Micklethwait said the outlet will carry polls, interview the candidates and track their campaigns. A reporter has been assigned to follow Bloomberg's campaign.

"We have already assigned a reporter to follow his campaign (just as we did when Mike was in City Hall)," Micklethwait said. "And in the stories we write on the presidential contest, we will make clear that our owner is now a candidate."

Bloomberg News' investigations into President Donald Trump will proceed undeterred.

"For the moment, our P&I team will continue to investigate the Trump administration, as the government of the day," wrote Micklethwait.

If Bloomberg becomes the Democratic presidential candidate and Trump is the Republican candidate, the news organization will "reassess how to do that," Micklethwait said.

Bloomberg is also suspending the board responsible for Bloomberg Opinion, "The place where Mike has had the most contact with Editorial," wrote Micklethwait.

He said David Shipley, Tim O'Brien and some members of the board responsible for those editorials will take a leave of absence to join Bloomberg's campaign.

O'Brien has a history with Trump himself. He published a book titled "TrumpNation" in the early 2000's, where he claimed Trump was not a billionaire. Trump sued O'Brien soon after the book was released but the case was later dismissed.

Columnists will continue to "speak for themselves" and take some op-ed articles from outsiders, though not those on the election, said Micklethwait.

In a separate memo from Mike Bloomberg to Bloomberg News employees on Sunday, the newly announced candidate said that during his campaign, he will turn leadership of the company over to a management committee.

"This is not the first time I've stepped away to run for office. And like the last time, we have put in place an outstanding leadership team to take the reins."