Democrats Have Two Paths for 2020: Daring or Defensive. Can they settle on Either?

But in an ominous result for Democrats, two swing states – Iowa and Ohio – appeared to move decisively away from them, and Florida, the country's largest swing state and another state Mr. Trump won in 2016, remained agonizingly elusive. Mr. Trump in 2020, it would leave Democrats squeezed across the rest of the map.

"To win the upper Midwest and Florida we have to do two things Obama was able to do: get exceptionally strong African-American turnout and also get a higher proportion of noncollege whites," said Robby Mook, who ran her. Clinton's campaign, adding that Mr. Obama's success was a reminder that he did not have an opportunity to defeat Mr. Trump.

"Barack Obama was not an old white guy but he checked these boxes," Mr. Mook said.

Because of the mixture of results Tuesday, there was little to discuss ambitious Democrats from moving ahead with preparations for 2020, most of them eyeing early announcements to avoid letting any competitors catch fire.

Ms. Harris, the senator from California, is seen by allies as soon as possible to announce a campaign early in next year, after the release of a book due in January. Her sister, Maya Harris, trained top adviser to Mrs. Clinton, has already been quietly gauging the intentions of some influential Democrats in order to have an early roster of supporters ready.

The Harris camp has been reached by a coalition of people who have been working in the field of fundraising. Mr. Vilsack and train Gov. James Hodge of South Carolina.

Allies of Mr. Booker, the senator from New Jersey, is in the process of becoming president of the country.

Multiple Democrats said that Addisu Demissie, who just ran the campaign of Gavin Newsom, the governor-elect of California, could only serve as an official in his book.