Former New York mayor Mike Bloomberg has decided to form an independent expenditure campaign that will absorb hundreds of his presidential campaign staffers in six swing states to work to elect the Democratic nominee this fall.

The group, with a name that is still undisclosed because its trademark application is in process, would also be a vehicle for Bloomberg to spend money on advertising to attack President Trump and support the Democratic nominee, according to a person familiar with the discussions, who spoke on the condition of anonymity to reveal internal deliberations.

The moves come as Bloomberg has continued to taunt Trump on social media, releasing a video Thursday on Twitter that cut together a number of clips in a way meant to mock Trump’s claims that he would win the White House, hold the Senate and take back the U.S. House.

The Post's Michelle Ye Hee Lee explains how billionaires like Mike Bloomberg and Tom Steyer changed the game as Democratic presidential candidates in 2020. (The Washington Post)

“We are not going anywhere. We will haunt your dreams. We are in your head,” the video declares in spliced-together clips from movies, television shows and music videos. “Starting today, and every day after that, every morning, every night, we will be here watching you, always watching, making sure everyone knows what a disaster you are.”

The new group, operating with the same potentially limitless bankroll that funded Bloomberg’s campaign, could play a major role in shaping the race this fall.

Bloomberg, who is worth more than $50 billion, also has not ruled out using the group to spend money to support former vice president Joe Biden during his primary fight against Sen. Bernie Sanders (I-Vt.). Bloomberg dropped out of the race Wednesday.

“I’ve always believed that defeating Donald Trump starts with uniting behind the candidate with the best shot to do it,” Bloomberg said Wednesday after his disappointing showing in the Super Tuesday primaries. “After yesterday’s vote, it is clear that candidate is my friend and a great American, Joe Biden.”

The promise of help has been welcomed by Biden, but advisers to Sanders have said they do not want any general election assistance from Bloomberg if their candidate wins the nomination.

Bloomberg’s advisers have identified Wisconsin, Michigan, Pennsylvania, Arizona, Florida and North Carolina as the six states that will decide the electoral college winner this year. Staffers in each of those states have signed contracts through November to work on the effort.

The new group also could serve as a vehicle for Bloomberg to support Democratic candidates for the House and Senate. In 2018, Bloomberg gave $20 million to Senate Majority PAC to support Democratic senatorial candidates. A separate group he founded, Independence USA, spent $38 million to help Democrats retake the U.S. House.

Some of the seats Democrats won in 2018 will have to be defended in 2020 in states, such as Pennsylvania and Michigan, where Bloomberg plans to have organizing teams through the fall. Democrats also see Senate pickup opportunities in Arizona and North Carolina, while Sen. Gary Peters (D) faces a potentially competitive reelection campaign in Michigan.

The Bloomberg operation could provide a major backstop to efforts by the Democratic National Committee and the remaining presidential campaigns, which have dramatically trailed the Republican National Committee and the Trump reelection campaign in fundraising as well as in preparing for a general election.

The Trump campaign reported $93 million in cash on hand at the end of January vs. $7 million reported by Biden and $17 million reported by Sanders.

Bloomberg also will continue to fund Hawkfish, a data effort to support Democratic campaigns. That operation is structured as a separate for-profit campaign vendor to Bloomberg’s campaign, the person familiar with the discussions said, so there is no need to reorganize its structure to allow it to work with the new group.

Hawkfish has signed a long-term lease in the same building in New York’s Times Square that houses Bloomberg’s presidential campaign. The campaign, by contrast, plans to wind down its lease at the property.

The Bloomberg campaign offices and staffs that remain in other states — he has 12 offices open in Ohio, for example — will be closed in the coming weeks. Staffers will be offered the chance to apply to do field work in the targeted general election states.

Because of campaign finance rules, Bloomberg’s aides have concluded that they cannot simply tell campaign employees to work directly for Biden. “The folks in those states have been told that they can apply for spots in the battleground,” said the person familiar with the plans.

At its peak, Bloomberg’s campaign boasted a staff of more than 2,100, including about 1,800 in state offices away from his New York headquarters. Since announcing his campaign in late November, he spent $558 million on advertising, according to the ad tracking firm Advertising Analytics.

“Today I am clear-eyed about our ultimate objective, and that is victory in November,” Bloomberg said Wednesday during a speech in New York City. “I will not be our party’s nominee, but I will not walk away from the most important political fight of my life.”