Former vice president Joe Biden, Sen. Bernie Sanders (I-Vt.) and Sen. Elizabeth Warren (D-Mass.) run strongest against the president nationally, with Biden leading by 17 points (56 percent to 39 percent), Warren by 15 points (55 percent to 40 percent) and Sanders by 14 points (55 percent to 41 percent).

South Bend, Ind., Mayor Pete Buttigieg and Sen. Kamala D. Harris (D-Calif.), the other two Democrats tested against Trump, also lead the president among registered voters, with Buttigieg up by 52 percent to 41 percent, and Harris ahead by 51 percent to 42 percent…

Nonetheless, the national results represent a shift away from Trump since the summer, when only Biden had a clear advantage over the incumbent. With Republicans and Democrats mostly locked in on their voting intentions, the biggest difference between the results from July and those in the new poll is that independents have moved in the direction of the Democratic candidates.

One wild card is any possible impact that the impeachment proceedings might have on public attitudes. The current poll was completed just before the House voted along party lines to formalize the inquiry.