WASHINGTON (AP) — Former New York City mayor Michael Bloomberg is officially a Democrat again.

The global media company founder on Wednesday said he has registered as a Democrat, which would be especially significant if he decides to challenge President Donald Trump in 2020. Bloomberg says on social media he did so "because we need Democrats to provide the checks and balance our nation so badly needs."

Bloomberg did not say when he might make a decision on running for president. He served three terms as New York City mayor and has variously been a Democrat, a Republican and an independent. He twice flirted with running for president as an independent candidate.

Bloomberg has thrown money and support behind Democrats and is attacking Republicans on abortion and gun policies.