Bernie Sanders has reached his highest level of support this year in the latest NBC News/SurveyMonkey online poll. Sanders is now the preferred candidate of 33% of Democratic and independent voters who lean Democratic. However, he still trails Hillary Clinton by 16 points, and his slight gain of 3 points since last month’s poll is barely perceptible and within the poll’s error estimate of plus or minus 3.1 percentage points. Martin O’Malley has struggled to make any kind of impact on Democratic voters, despite now having been on a national debate stage twice with his rivals.

PHOTOS - On the Stump: Bernie Sanders' Presidential Campaign

The latest NBC News/SurveyMonkey online poll was conducted Sunday through Tuesday among 5,755 adults nationwide, including 1,983 Democratic voters and independent voters who lean Democratic. Sanders maintains a strong lead among young voters, and he trails Clinton by a mere 3 points among whites, 6 points among men, and by 9 points among college graduates. But among all other groups, Clinton continues to hold double-digit leads.

Stephanie Psyllos, Hannah Hartig, and Josh Clinton contributed reporting.

The NBC News/SurveyMonkey online poll was conducted from November 15-17, 2015 among a national sample of 5,755 adults aged 18 and over and including a sample of 1,983 Democratic voters and independent voters who lean Democratic. Respondents for this non-probability survey were selected from the nearly three million people who take surveys on the SurveyMonkey platform each day. Overall results have an error estimate of plus or minus 1.9 percentage points and the error estimate for the leaned Democratic voters is plus or minus 3.1 percentage points. A full description of our methodology and the poll can be found here.

The poll was produced by the Data Analytics Lab of NBC News in conjunction with Penn’s Program on Opinion Research and Election Studies with data collection and tabulation conducted by SurveyMonkey.