Bloomberg spends another $10 million to boost Democrats in final days of midterms

The majority of the new cash will fund an ad buy though Independence USA PAC, Bloomberg's super PAC. The ad will begin airing on television and online in eight cities -- Chicago, Seattle, Detroit, Kansas City, Miami, Orlando, Portland and Atlanta -- on Friday. The ad will also air on national cable outlets, including MSNBC and CNN.

The ad buy from Bloomberg comes during what has become an active midterm cycle for a politician who is openly flirting with a 2020 run.

The ad slams Republicans for failing to deliver policies that benefit the middle class and suggests that the Democrats are more committed to cutting taxes for the middle class and ensuring health coverage for people with pre-existing conditions.

"In Washington, one party is calling the shots and the middle class isn't being heard," a narrator in the ad.

"It's clearer than ever that we need a new Congress," Bloomberg said. "With the midterm elections less than two weeks away, we're taking this message from coast to coast and urging voters to elect Democrats to the House and the Senate."

Bloomberg, who served three terms as mayor, has been crisscrossing the country to speak at events and fundraisers in support of Democratic candidates. During the stops, Bloomberg frequently criticizes Trump's policies and chides Republicans for failing to serve as a check on Trump, stoking further speculation Bloomberg will run for president — an idea he's flirted with during the lead-up to previous election years.

Democrats in Washington took Bloomberg's presidential ruminations more seriously, however, after he pledged in June to spend $80 million on behalf of Democrats in the 2018 midterms. He later upped the number to $100 million, a massive amount that has amplified Republican concerns in Washington that Democrats will be able to bury them in ads for the final weeks of the campaign.

Bloomberg is already spending on key contested races in expensive media markets. On Thursday, for example, Independence USA will spend $4.5 million for Katie Hill and $4.1 million for Harley Rouda, according to the Federal Election Commission, two California congressional candidates looking to unseat Republicans in the expensive Los Angeles media market.

While Bloomberg's giving will give him credibility with Democrats, should he decide to run in 2020 he will have marked hurdles to overcome, too -- namely the fact that Wall Street, something synonymous with the centrist former mayor, has become a bogeyman in left-leaning Democratic politics.

Before running for mayor of New York, Bloomberg was a Democrat. He switched parties, registering as a Republican in 2000 to get on the ballot. The Democrats were backing another candidate. Bloomberg switched parties again and registered as an independent in the summer of 2007. Earlier this month, he re-registered as a Democrat.

"Even as I support Democrats this fall, I will always believe no party has a monopoly on good ideas. Both sides can learn from each other if we are willing to listen to one another," Bloomberg said at CNN's CITIZEN conference earlier this week.