"He's not going to do well, but I think he's going to hurt [Democratic candidate Joe] Biden, actually, but he doesn't have the magic to do well", Trump said. "Little Michael will fail".
Trump pointed out that he knows Bloomberg fairly well and would be happy if he did end up doing well.
The statement comes after The New York Times reported on 7 November that Bloomberg is expected to file paperwork by the Friday deadline to enter the Democratic presidential primary.
Bloomberg adviser Howard Wolfson said in a series of tweets said the former mayor fears that no Democratic candidate currently running will beat Trump in the 2020 race.
Bloomberg is expected to file documentation this week to put his name on the ballot in at least one state, The New York Times reported earlier citing people briefed on the matter. Michael Bloomberg, facing an 8 November deadline, dispatched staffers to Alabama to gather signatures to qualify in the state’s primary, according to the report.