The former Mayor of New York Michael Bloomberg has announced a bid for the 2020 Democratic presidential nomination.

It follows weeks of speculation that the billionaire would run for president.

On twitter this afternoon, he said he was “running for president to defeat Donald Trump and rebuild America.”

"We cannot afford four more years of President Trump’s reckless and unethical actions," he said.

"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.

"The stakes could not be higher.

“I believe my unique set of experiences in business, government and philanthropy will enable me to win and lead."

Mr Bloomberg has reportedly already spent $31m (€28m) on a TV advertising campaign that promises to “rebuild the country and restore faith in the dream that defines us: where the wealthy will pay more in taxes and the middle class get their fair share.”

I’m running for president to defeat Donald Trump and rebuild America.

I believe my unique set of experiences in business, government, and philanthropy will enable me to win and lead.

Join our team: https://t.co/7ezlUeouqH pic.twitter.com/IyOeS3aWaF

— Mike Bloomberg (@MikeBloomberg) November 24, 2019

Mr Bloomberg’s campaign said he would not be accepting donations and will remain self-funded.