The Jewish billionaire businessman and three-term NY mayor said Wednesday he has registered as a Democrat, which would be especially significant if he decides to challenge President Donald Trump in 2020.
Bloomberg was elected mayor of New York City as a Republican in 2001 and re-elected in 2005. Today, he released a picture of himself filling out his registration form and warning about threats to the Constitution that require checks and balances.
"At key points in US history, one of the two parties has served as a bulwark against those who threaten our Constitution", Bloomberg writes.
Bloomberg, who served three terms as mayor, is the founder and owner of Bloomberg L.P., a global financial services and media corporation.
Bloomberg's new party affiliation will likely fuel further speculation about a 2020 presidential run.
Bloomberg has drifted between political parties throughout his life - going from Democrat to Republican to independent to, now, Democrat again.
The change in party affiliation comes after Bloomberg chose to spend millions in the 2018 election to help elect Democrats. His advisers told the Washington Post this month, amid the contentious fight over the confirmation of Supreme Court Justice Brett Kavanaugh, that he would spend an additional $20 million to help Democrats retake the U.S. Senate. He campaigned for Hillary Clinton in 2016 and gave a speech supporting her nomination at the Democratic National Convention.
His change is seen as a possible move to running for president in 2020.
Bloomberg, 76, was a longtime Democrat who became a Republican before running for mayor of the largest USA city in 2001.