Washington — Former New York Mayor Michael Bloomberg formally announced he is running for the Democratic presidential nomination Sunday, launching a multimillion-dollar ad campaign that frames his candidacy as the best hope for defeating President Trump.

Bloomberg's first minute-long advertisement will debut nationally on "60 Minutes" on Sunday evening, and appear again on NBC Sunday Night Football. It will begin airing across most Super Tuesday states Monday, according to a campaign aide. The former mayor is spending at least $34 million on the ad, which will run through December 3.

Keeping with his long-standing practice, Bloomberg will self-fund his campaign and doesn't plan on accepting campaign contributions. If elected president, he would not accept a salary, according to aides.

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Turning down campaign contributions means he won't be eligible to appear in Democratic debates, which require candidates to obtain a certain number of donors under current party rules.

"If the DNC changes the rules and Bloomberg is eligible, obviously he will appear," spokesman Jason Schechter said.

Bloomberg, 77, is a media mogul and former three-term mayor of New York. He has toyed with running for president as an independent or Democrat since 2008. He enters the field far back in an historically crowded field, according to recent CBS News polling that placed him in the single digits among Democrats from early primary states.

In a letter on his revamped website Sunday, Bloomberg wrote that the country "cannot afford four more years of President Trump's reckless and unethical actions."

"He represents an existential threat to our country and our values. If he wins another term in office, we may never recover from the damage," he wrote.

The ad released Sunday says Bloomberg "could have just been the middle class kid who made good," but instead "became the guy who did good."

"After building a business that created thousands of jobs, he took charge of a city still reeling from 9/11," the narrator says. "A three-term mayor who helped bring it back from the ashes, bringing jobs and thousands of affordable housing units with it. After witnessing the terrible toll of gun violence, he helped create a movement to protect families across America and stood up to the coal lobby and this administration to protect this planet from climate change."

The ad says he will seek to "restore faith in the dream that defines us where the wealthy will pay more in taxes and the middle class get their fair share. Everyone without health insurance can get it, and everyone who likes theirs, keep it." It ends with a tagline: "Jobs creator. Leader. Problem solver."

Bloomberg News editor-in-chief John Micklethwait informed employees that the news division won't be doing any investigations of Michael Bloomberg and his family during the campaign, a courtesy it will also extend to Bloomberg's rivals in the Democratic presidential primaries.

He explained in a memo Sunday that Bloomberg News "cannot treat Mike's Democratic competitors differently from him." Micklethwait said that Bloomberg News would publish articles or summaries of investigative work by other "credible journalistic institutions."

Should Bloomberg be chosen as the Democratic nominee, Bloomberg News will reassess how it will cover him, Micklethwait added.

The editors of Bloomberg's Opinion page, which "reflected his views," David Shipley, Tim O'Brien, as well as some members of the Board responsible for the editorials will be taking a leave of absence to join Bloomberg's campaign, Micklethwait also announced.