Republicans nationwide have downgraded their opinions of Donald Trump, Ben Carson and Jeb Bush three weeks before the first presidential caucuses and primaries begin, even as increasing numbers view Ted Cruz and Chris Christie in a positive light, according a new Washington Post-ABC News poll.

The poll finds far less upheaval on the Democratic side, with Hillary Clinton receiving persistently high favorable marks among fellow Democrats and outpacing Bernie Sanders across all segments of the party. Her popularity advantage nationally contrasts with polls in Iowa and New Hampshire showing competitive contests for the nomination.

[Read poll results and methodology]

Among the overall public, broad impressions of candidates range from mediocre to historically negative. Sanders ranks best with a narrowly positive image at 44 percent favorable and 40 percent unfavorable, followed by a slew of candidates in narrowly negative territory, and Jeb Bush and Donald Trump receiving clearly negative reviews.

Former President Bill Clinton wins higher favorable marks — 53 percent — than any major 2016 candidate, having only recently joined the campaign trail to support Hillary. Still, even his numbers are down 10 percentage points from the spring of 2014.

While no candidate is liked by a majority of Americans, Trump's and Bush's ratings are significantly worse at this point than any candidates since 1984 who have won their parties' nominations. Trump's net favorable rating (percent favorable minus percent unfavorable) is -27, while Bush's is -23.

The closest analog is Mitt Romney, who held a net negative rating of -15 in January 2012 and -16 in March of that year. George W. Bush held very typical ratings in February 2000 with a plus-10 net favorable rating. Jeb Bush and Trump's ratings are closer to those of Newt Gingrich in early 2012, who held a -22 net favorable rating in January and -28 rating in March. (Gingrich, of course, lost the nomination fight to Romney.)

Even then, though, Trump's 48 percent "strongly unfavorable" rating far exceeds Gingrich's high of 35 percent, in part due to much fewer respondents offering "no opinion" of Trump.

Republican shakeup

Republicans give Carson, Cruz and Marco Rubio the highest net favorable ratings in the poll, followed Christie, Trump and Bush.

Both Cruz and Christie made gains from their standing among Republicans in previous Post-ABC polls, with Cruz's favorable rating growing from 44 percent in May to 53 percent in November and 60 percent today. Christie's rise over a longer time-span, from 35 percent in May 2015 to 53 percent in the latest survey, is driven by a 26-point rise in favorable impressions among conservative Republicans.

Both Ben Carson and Donald Trump have lost ground since topping the GOP field in November with favorable ratings of roughly 70 percent among fellow Republicans. Trump's favorable rating has fallen 12 points to 57 percent, while Carson's has slipped nine points to 62 percent — still numerically the highest in the field, despite his decline in Republican primary polls. Trump's decline has been concentrated among Republicans without college degrees — typically one of his strongest groups in polls.

Bush stands at his lowest point among Republicans in Post-ABC polling, with 44 percent saying they have a favorable impression of the former Florida governor and 50 percent rating him negatively. In November, Bush's image tilted positive by a 56-37 margin. Bush's falling favorability has been concentrated among Republican men (down 21 points from November) and self-identified conservatives (down 15 points).

Rubio's image has shown the greatest stability since November; roughly twice as many report favorable as unfavorable ratings (58-28), with positive marks unchanged and negative ratings ticking up six points in the past two months and 12 points since last spring.

Democrats' stability

Clinton continues to receive overwhelmingly positive ratings from Democrats nationally, with 84 percent rating her favorably and 15 percent unfavorably — almost identical to her 83-14 split in November. Sanders is rated positively by a 58-31 margin — also very similar to a 54-25 margin in the previous survey.

National impressions have the potential to shift after early nomination contests in Iowa and New Hampshire; polls show Sanders and Clinton in a tight race in Iowa, while Sanders has an apparent lead in New Hampshire. It's unclear how much Sanders appeal will extend beyond these early contests, including states with large African American and Hispanics populations who have been more supportive of Clinton this cycle.

Sanders appears to have made some gains with African-American, Hispanic and other non-white Democrats, however. By 51 percent to 32 percent, more non-white Democrats offer favorable than unfavorable impressions of Sanders, compared with a 36-29 favorable-unfavorable split in October and 41-31 margin in November.

Clinton still outpaces Sanders across all demographic subgroups of Democrats — most notably, non-whites (92 percent favorable) and liberals, with whom 88 percent rate Clinton positively and 74 percent say the same of Sanders. But Clinton's advantage in favorable ratings is clearest among moderate and conservative Democrats, among whom 80 percent give Clinton favorable marks but only 41 percent rate Sanders positively.

The Post-ABC poll was conducted Jan. 6-10 among a random national sample of 1,000 adults reached on conventional and cellular phones. Overall results have a margin of sampling error of plus or minus four percentage points; results among the sample of 277 Republicans have an 7.5-point error margin and results among 316 Democrats have an seven-point error margin.