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.

Billionaire Mike Bloomberg is prepared to spend well over the $100 million he put into his last campaign for New York City mayor if he runs for president in 2020. And he does not plan to accept any outside money from political action committees if he jumps into the race, CNBC has learned.

Howard Wolfson, Bloomberg's top political advisor, in an email hinted at how much his boss would look to invest into his own potential campaign for president.

"Mike spent more than $100 million in his last mayor's race. Last time I looked, NYC is a fraction of the size of the country as a whole," he explained. The last time he ran for public office was in 2009, when he ran for re-election as mayor for a third term and pulled off a victory as an independent.

Bloomberg spent more than $110 million backing Democrats during the 2018 congressional midterm elections. When asked if he would spend at least that on his own campaign, Wolfson replied, "Whatever is required."

If the former New York City mayor contributes that much to his own coffers, he will have one of the largest 2020 war chests and a stark advantage over other potential Democratic hopefuls, such as former Vice President Joe Biden, Sens. Cory Booker, Elizabeth Warren and Kamala Harris and Texas Rep. Beto O'Rourke.

Still, being a successful businessman may not be what voters are looking for as an alternative to Trump, especially as the party veers toward a progressive platform.

In the latest Quinnipiac University poll, Bloomberg had an overall unfavorable rating of 32 percent, and 19 percent of Democrats participating viewed him negatively. However, 44 percent of those who were asked about their perception of Bloomberg said they haven't heard enough to make a decision.

Meanwhile, Biden led in the poll, with 84 percent of Democrats saying they favor him over other candidates.

The 2018 congressional midterms were also, in part, a reflection of the shifting landscape for the Democratic Party as liberal congressional candidates such as Alexandra Ocasio-Cortez swept away establishment Democrats in primaries and others unseated Republicans in the general election.