Trump just kicked the slats out from the democrats.
For a long time democrats have been expanding the campaign season.
Remember that Barack Obama officially announced his first candidacy in February 2007 - a full 21 months before the election.
And they usually start talking and hinting about a candidacy long before that.
So once again, Trump has beat them at their own game.
And I believe there are some rules that allow him to do certain things as an announced candidate that he cannot do otherwise.
President Trump filed some paperwork for a 2020 run on Inauguration Day.
This paperwork was a block to nonprofits, so they couldn’t campaign against him early on (h/t t Ruth):
http://www.freerepublic.com/focus/f-news/3550555/posts?page=50#50