NBC News reports:
Michael Bloomberg announced Wednesday that he had re-registered as a Democrat, in a sign that the former New York City mayor could be seriously considering a presidential bid in 2020.
“At key points in U.S. history, one of the two parties has served as a bulwark against those who threaten our Constitution. Two years ago at the Democratic Convention, I warned of those threats,” Bloomberg announced in a post on Instagram that he also shared on Twitter.
Bloomberg had been a Democrat prior to his initial mayoral run in 2001, when he became, and was elected as, a Republican. He was re-elected in 2005 as a Republican, but then became an independent in 2007 and was re-elected to a third term in 2009 as an independent.
— Mike Bloomberg (@MikeBloomberg) October 10, 2018