Bernie Sanders’ lead is increasing with Democratic primary voters in New Hampshire, according to a new CNN/WMUR poll.

The Vermont senator has 50 percent of Democratic primary voters, a 4 percent increase since September. Former Secretary of State HIllary Clinton comes in 10 percentage points behind Sanders with 40 percent, though her total has increased by 10 percentage points since September. Former Maryland Gov. Martin O’Malley is barely registering — he fell from 2 percent to 1 percent.

The majority of Clinton’s bump comes from the exit of Vice President Joe Biden, who was factored into the September poll and was supported by 14 percent of those surveyed. In October, after much speculation, he announced he would not enter the race.

In Wednesday's poll, 15 percent of those polled said they would not support Clinton under any circumstances. The percentage of people who would refuse to vote for Sanders held steady at 5 percent.

Despite Sanders’ overall lead, 59 percent of New Hampshire Democrats believe Clinton is most likely to win their primary. That’s nearly 20 percent higher than in September, when she was tied with Sanders at 42 percent. The Vermont lawmaker has seen his figure decrease to 28 percent.

But the numbers are still fluid. Just 36 percent of New Hampshire’s likely Democratic primary voters know who they’ll support. Twenty-one percent are leaning toward someone, and 44 percent are still open to persuasion.

The poll of 370 likely Democratic primary voters in New Hampshire was taken between Nov. 30 and Dec. 7 by telephone. The margin of error is plus or minus 5.1 percentage points.