The new poll finds Clinton with 37% support among Democratic and Democratic-leaning voters, down 10 points since August, followed by Vermont Sen. Bernie Sanders at 27% and Vice President Joe Biden at 20%. Sanders' support is about the same as it was in August, making Biden the only candidate to post significant gains in the last month. His support is up 6 points in the last month as he weighs making a run for the presidency.
Behind the top three, former Maryland Gov. Martin O'Malley holds 3%, former Virginia Sen. Jim Webb is at 2% and former Rhode Island Gov. Lincoln Chafee logs less than 1% support.
In the general election matchups, Clinton trails former neurosurgeon Ben Carson by a significant margin (51% Carson to 46% Clinton among registered voters) while running about evenly with both former Florida Gov. Jeb Bush (49% Bush to 47% Clinton) and businessman Donald Trump (48% back each).
The shift away from the former secretary of state stems from shrinking support among women. Clinton's advantage among women has disappeared in matchups against Bush and Carson. Facing Trump, Clinton still carries women by a large, though tighter, margin. In August, 60% of women favored Clinton to 37% for Trump, but that's narrowed slightly to 55% Clinton, 41% Trump now. Clinton's advantage among women against Trump is fueled by independent women, despite that group shifting away from Clinton in the head-to-head against Bush.
The poll suggests Republican women have consolidated their support around their party's front-runners in the last month, and are now more apt to back both Bush and Trump than they were a month ago. At the same time, the near-universal support for Clinton among Democratic women has softened slightly, bringing it more in-line with her support among Democratic men.
With Biden's consideration of a run for the White House gaining attention, the poll finds he outperforms Clinton in these hypothetical general election matchups, topping Bush and Trump while falling just slightly behind Carson. Biden tops Trump by 10 points (54% to 44% among registered voters), leads Bush by 8 points (52% to 44%) and is 3 points behind Carson (50% Carson to 47% Biden). Biden's advantages against Bush and Trump rest on the same kind of gender gap that Clinton appears to have lost: Biden leads Bush by 16 points among women while tying him among men, he tops Trump by 26 points among women while trailing him by 7 among men, and he leads Carson by 5 among women while trailing by 10 among men.
The poll also finds Democrats' overall enthusiasm for Clinton has waned. In April, shortly after she launched her campaign, 60% of Democratic and Democratic-leaning voters said they would be enthusiastic about her candidacy should she win the party's nomination for president. Now, just 43% feel that way. But neither Biden nor Sanders has mustered that level of enthusiasm among the Democratic faithful, 37% say they would be enthusiastic about Biden, 31% about Sanders. And Sanders prompts the greatest potential dissatisfaction, with 30% saying they would be dissatisfied or upset if he eventually won the party's nomination.
Clinton's fade in the Democratic race comes as an ideological divide within the party grows into a chasm. In August, Clinton held support from 43% of moderates and 46% of liberals. In the new poll, her support among moderates holds at 47%, while among liberals, it has plummeted to just 23%. Sanders has increased his share of the liberal vote (from 42% to 49%), while falling 9 points among moderates (from 24% to 15%). Meanwhile, Biden has gained ground in both groups.
And enthusiasm for Clinton among liberals has fallen nearly 40 points. Just 29% of liberal Democrats say they would be enthusiastic if she were the party's nominee, down from 68% in an April poll.
Asked why they back their candidate, most Clinton supporters said her experience is the draw: 58% say it's mostly on account of her on the job experience, 32% because of her positions on the issues, and 9% because they don't like the other candidates. Among those Democrats backing her rivals for the nomination, 55% say their choice was driven by the candidate's positions on the issues, while 27% cite experience and 17% say it's due to dislike of the other candidates.
There is some good news for Clinton in the poll, however, since most Democrats still say they expect her to be the party's eventual nominee and the more enthusiastic Democratic voters are more apt to be Clinton backers. Among Democrats and Democatic-leaning voters, 65% expect Clinton to top the party's ticket in 2016. And among those Democratic voters who say they are extremely or very enthusiastic about voting for president next year -- a group which may be more likely to cast ballots in next year's primary contests -- 42% back Clinton, 29% Sanders and 15% Biden.
The CNN/ORC Poll was conducted by telephone September 4-8 among a random national sample of 1,012 adults. This sample included 930 interviews with registered voters, 395 of whom were self-identified Democrats or Democratic-leaning independents. For results among all registered voters, the margin of sampling error is plus or minus 3 percentage points. Among Democratic voters, it is plus or minus 5 points.