The 77-year-old businessman is planning to file paperwork this week to declare himself as a Democratic candidate in Alabama – where there is an early filing deadline, as reported by multiple media outlets Thursday.
Bloomberg's adviser, Howard Wolfson, confirmed that he is taking steps to enter the race.
"Mike believes that Donald Trump represents an unprecedented threat to our nation," Wolffson said in a statement. "We now need to ... ensure that Trump is defeated -- but Mike is increasingly concerned that the current field of candidates is not well positioned to do that."
The New York Times, citing people briefed on Bloomberg’s plans, reported he has been weighing a bid for weeks but has sent staffers to Alabama to gather signatures to qualify for the state’s primary.
With more moderate views, Bloomberg could draw voters away from former Vice President Joe Biden.
Bloomberg – a Republican-turned-Democrat – announced in March that he did not plan to run for president, saying at the time he was “clear-eyed about the difficulty of winning the Democratic nomination in such a crowded field.”
Bloomberg had indicated that he was prepared to divest his company in pursuit of his return to politics.
During an interview with Iowa Radio in December, Bloomberg said if he runs for president, he would either sell the Bloomberg media company or place it in a blind trust. A blind trust is a financial arrangement by which a person cedes control, but not ownership, of business management to an independent trust to avoid conflicts of interest.
“But I think at my age, if selling it is possible, I would do that,” he said. “At some point, you’re going to die anyway, so you want to do it before then.”
The Bloomberg media company has an estimated valuation of $50 billion and generated $9.6 billion in revenue in fiscal 2017, according to Forbes. As its founder, he owns 88 percent of the company and has an estimated personal net worth of $47 billion.