This article is the first in a two-part series for the Debatable newsletter about the 2020 presidential election. Thursday’s edition will cover Republican prospects next November. You can sign up here to receive Debatable on Tuesdays and Thursdays.

Assuming the role once again of party buzzkill in chief, the House speaker, Nancy Pelosi, issued a warning on Friday that some Democratic presidential candidates, in her view, are too far left. “What works in San Francisco does not necessarily work in Michigan,” Ms. Pelosi told Bloomberg News, stamping out policy ideas, such as the Green New Deal and Medicare for All , that have caught fire on the party’s progressive wing. “Remember November,” she said. “You must win the Electoral College.”

Astead Herndon, a Times political reporter, swooped in on Twitter, pointing out that the ideological landscape of the country is not that neatly mapped: As any Bernie Sanders supporter worth her fair- trade salt will tell you, it was he who won the 2016 Democratic primary in Michigan. But one year from the general election, a new Times poll suggests that Ms. Pelosi may have a point: Across six battleground states, only Joe Biden leads President Trump, narrowly, among registered voters; Mr. Sanders finds himself in a deadlock, while Elizabeth Warren trails the president by two percentage points.

Of course, as 2016 so colorfully illustrated, polling is hardly an exact science, especially this far out from an election. But the Times data offers little hope that the Democrat ic Party’s existential angst over how to resuscitate itself will be resolved anytime soon.