A new CNN poll shows former Secretary of State Hillary Clinton with an increased lead over Sen. Bernie Sander, I-Vermont, though the specter of a potential challenge from Vice President Joe Biden still looms large.
Forty-two percent of Democratic primary voters nationally support Clinton, 24 percent support Sanders and 22 percent support Biden and 1 percent support former Maryland Gov. Martin O'Mally, the poll shows. A CNN poll from early September had Clinton leading Sanders by just 10 points, 37 percent to 27 percent, with Biden getting 20 percent support.
The poll also finds that Clinton stands to gain the most if Biden does not enter the race. Without his name in the mix, her support goes up by 15 percentage points, versus just 4 points for Sanders. Then, her lead over Sanders nationally would be nearly double, 57 percent to 28 percent.
Biden is still deciding whether to leap into the 2016 race. Last week he met with political advisers at his residence in Washington, D.C. A spokesman for his wife, Jill Biden, said over the weekend that that the vice president's wife "would be on board" if he ran.
The poll surveyed 392 Democrats and Democratically-leaning independents from September 17 to19 and has a margin of error of plus or minus 5 points.
An earlier version of this story incorrectly stated Sanders' support in an early September poll. It was 27 percent.