Joseph R. Biden Jr. is “sleepy,” Bernie Sanders is “crazy” and Elizabeth Warren is “angry.” Since January, President Trump has attacked several of the Democrats competing for his job — some more than others.

Mr. Trump’s habit of hurling insults and childish taunts at rivals is extraordinary for a sitting president; while his behavior is well-known by now, politicians in both parties have warned against becoming numb to it, saying that Mr. Trump is debasing the country with his personal attacks. As Mr. Trump seeks to tear down his rivals in the 2020 race, here are the candidates Mr. Trump has insulted so far.

This analysis is based on statements Mr. Trump has made on Twitter, in speeches and at campaign rallies. It does not include interviews or other interactions in which he may have been asked about specific candidates.

The president appears to be focusing on the leading candidates, especially when they are enjoying an upsurge in media coverage. These candidates account for just a fraction of the hundreds of people, places and things he has insulted on Twitter and elsewhere.