CNN News:21人宣布参加2020年美国总统大选

The date of this show is May 2, 2019, which means we're almost exactly a year and a half from the next U.S. presidential election. And 21 people have already declared their candidacy for president in addition to the incumbent leader himself.
President Donald Trump filed his re-election paperwork just hours after he was inaugurated on January 20, 2017. One candidate, a former governor of Massachusetts, has said he'll challenge President Trump for the Republican nomination. And as far as democrats go, there are 20 — a record number of them — who've officially announced their candidacy.
They include a former U.S. vice president, a number of senators and representatives, some mayors, an author, a former cabinet official. But why are these campaigns seemingly in full swing when we're still more than eight months away from even the first primaries and caucuses that help determine the party nominees? Money is one reason.

Fund raising is a critical part of any presidential run. And announcing early helps candidates start getting the donations that'll help fuel that run. Another reason — getting their name out there. Candidates need voters to be familiar with them, so this is a chance for presidential hopefuls to make connections well ahead of the elections.
Also, debate season is just around the corner. It kicks off at the beginning of summer and runs through next spring. So the candidates are working to qualify so they can get their faces and their messages on the national stage.