The Democratic National Convention is not until July 13–16, 2020.
I don't believe we have ever had a US President like Trump, enamoring his core support and driving hate in every other way. With a field that had 26 and is now about 20, Democrats are undecided.
The Democrat Primaries are
February 3 Iowa caucus, February 11 New Hampshire, February 22 Nevada caucus, February 29 South Carolina
March 3 (Super Tuesday): Alabama, American Samoa, Arkansas, California, Colorado, Massachusetts, Minnesota, Maine, North Carolina, Oklahoma, Tennessee, Texas, Utah, Vermont, Virginia
As of September 23
Biden 30.2, Warren 19.8, Sanders 16.6, Buttigieg 6.2 are not out of the running.
Harris 6.0, O'Rourke 3.2, Yang 3.0, Booker 2.8, Klobuchar 1.6, Gabbard 1.0 are probably next to impossible to actually become President and should not be nominated.
Tom Steyer showing 0.8% is an interesting one, with a lot of his own money and a personal commitment that his wealth will go almost entirely to charity. He's buying a lot of air time, and actually would make a fine President. He has unique characteristics and I would not rule him out at this time.
The bottom group of less than 1% each don't have the resources or support and should be dropping out.
Castro, Bennet, Delaney, Bullock, Williamson, Ryan, Sestak
Biden, Warren, Buttigieg, Steyer can each mount a campaign that could crush Trump.
Sanders is too radical and I see the country in a mess with the same internal war with a different President. I wish he eliminates himself because if he runs third party in November 2020, Trump wins easily.
Regardless of thumbs-down or up, I know that each of the four would make an excellent President and world leader. Each of the four are running with an intent to heal a divided nation. They run to serve the country. They run to distribute wealth better, but do it in gradual change with great care. All four support the Midwest working class and farmers. Each has personal strengths, but I'll stop here.
Anyone who truly cares about the USA, should listen to some interviews and speeches by these four.