 -- Hillary Clinton maintains a commanding lead for the Democratic presidential nomination heading into tomorrow’s ABC News debate –- but with notable weakness on honesty and trustworthiness, a challenge not just in the primaries but in a potential general election contest ahead.

Clinton leads Bernie Sanders by 31 percentage points, 59-28 percent, among Democrats and Democratic-leaning independents who are registered to vote in the latest ABC News/Washington Post poll, with Martin O’Malley in the single digits.

Clinton’s advantage over Sanders exactly matches its average in ABC/Post polls since September. That said, a candidate’s standing today is not necessarily predictive of his or her performance tomorrow: Clinton led Barack Obama by a similar margin, 28 points, in an ABC/Post poll at this time in 2007. Yet Obama rebounded to win the nomination.

See PDF with full results here.

And Clinton does have a prominent difficulty –- a trustworthiness deficit. Even with her overall lead, 44 percent of leaned Democrats say Sanders is more honest and trustworthy, vs. 38 percent who pick Clinton. She’s particularly vulnerable in this area among whites (a 26-point Sanders advantage) and political independents (Sanders +25).

Clinton manages 30 percent support from those who see Sanders as more honest and trustworthy, one reason her overall support overcomes the trust deficit. Further, she far surpasses Sanders on other measures in this poll, produced for ABC by Langer Research Associates – by 64-26 percent on who’d better handle the threat of terrorism, 54-37 percent on who’s closer to potential voters on the issues and 51-38 percent in empathy, as well as her lead in vote preference.

Clinton’s support is very near her average, 63 percent, in 10 ABC/Post polls to include her and Sanders this cycle, with a range from 56 to 69 percent. Sanders, for his part, peaked at 34 percent last month before slipping back in this survey. O’Malley’s 5 percent, low as it is, is a new high for him.

As covered earlier this week, in a general election matchup Clinton holds a slight 6-point advantage among registered voters vs. Republican frontrunner Donald Trump, 50-44 percent, compared with a 46-43 percent result against him in September.

Groups

Sanders’ gain last month was propelled by improvements among younger adults, women, nonwhites, liberals and those without a college degree. This month he’s seen a pullback in those same groups, and trails Clinton by double digits in all but one – leaned Democrats under age 40, among whom Sanders and Clinton run evenly.

Clinton, for her part, peaks with a 49-point lead over Sanders among nonwhites, 48 points among those 40 or older and 48 points among those who prefer someone with political experience over an outsider. She benefits heavily from the fact that leaned Democrats prefer experience by a broad 76-18 percent -– a vastly different picture than the Republican contest.

Clinton’s also ahead of Sanders by 38 points among Democrats, 33 points among moderates, 36 points among women and 34 points among those without a college degree.

Clinton’s support among some groups differs compared with this point in 2007 (when John Edwards also was in the race, with 12 percent support). Her backing is 21 points higher now than then among those age 40 and older, 19 points among college graduates, 15 points among women, 12 points among Democratic-leaning independents, 11 points among moderates and 10 points among nonwhites. It’s also 13 points lower among those under 40 -– and it’s those younger adults who now are most likely to side with Sanders on who’s more honest and trustworthy.

Methodology

This ABC News/Washington Post poll was conducted by landline and cellular telephone Dec. 10-13, 2015, in English and Spanish, among a random national sample of 1,002 adults. Results have a margin of sampling error of 3.5 points, including the design effect, for the full sample, and 5.5 points for registered leaned Democrats. Partisan divisions are 33-23-34 percent, Democrats-Republicans-independents.

The survey was produced for ABC News by Langer Research Associates of New York, N.Y., with sampling, data collection and tabulation by Abt-SRBI of New York, N.Y. See details on the survey’s methodology here.