Yet, he could be on the verge of backing several candidates that have vowed not to support Pelosi for speaker if the Democrats flip the House of Representatives during the 2018 congressional midterm elections. Bloomberg has promised to spend $80 million to help the Democrats accomplish just that in November.
In a statement to CNBC, Bloomberg praised Pelosi for their work together when he was mayor and said she's an "effective leader."
"I think she has been a very effective leader and that she was always there for the city when we needed her," Bloomberg said.
The two spoke over the phone this week about Bloomberg's new efforts and those close to her say Bloomberg's involvement in the 2018 midterms is a "major development," according to a person with direct knowledge of the matter.
Howard Wolfson, a former executive director of the Democratic Congressional Campaign Committee who runs Bloomberg's political operation, noted that Bloomberg has not decided who he will support in the runup to the November election.
Even so, Wolfson said he "imagine[d] there would be some overlap between candidates" supported by his boss and those backed by Rep. Seth Moulton, D-Mass., a vocal critic of Pelosi. Moulton recently created a political action committee, Serve America, which exclusively backs military veterans running for Congress who are looking to flip Republican districts.
Wolfson also said there will likely be "overlap" between the lists of candidates linked to Pelosi and the DCCC.
At least 11 of the 18 candidates Moulton supports have publicly denounced Pelosi as the party's leader and have called for change. One of them is Gil Cisneros, who is running to replace outgoing Republican Ed Royce in California's 39th District.
"While I respect Leader Pelosi's years of advocacy on behalf of California and the Democratic Party, it's time for new leadership," Cisneros told the San Francisco Chronicle on Thursday.
When asked if Bloomberg would back candidates that have declared they will not vote for Pelosi as speaker, Wolfson said, "It's impossible to say, given that we aren't close to finalizing our list."
A spokesman for Moulton says that being anti-Pelosi is not one of the criteria for being backed by their political organization. He also confirmed that Moulton and Bloomberg have had "great meetings" about Serve America's candidates. He declined to get into further details about those discussions.
A spokesman for Pelosi said she "has always enjoyed the overwhelming support of House Democrats and that will continue into the majority she's so focused on winning. Democrats don't let Republicans choose our leaders."