Sanders has consolidated much of his support among voters on the party’s left wing. Among those who call themselves liberals, Sanders has 49 percent, 30 points ahead of Buttigieg (19 percent) and Warren (15 percent).

But among those who consider themselves moderate or conservative, it’s Buttigieg (24 percent) who leads Biden (15 percent) and Sanders (13 percent).

Sanders, 78, is the oldest candidate in the race, but he’s the top choice among younger voters: He wins 51 percent of voters under age 35, and 32 percent of those aged 35 to 49.

The 38-year-old Buttigieg, meanwhile, is the leading candidate among primary voters 65 and older, even edging Biden among that bloc, 27 percent to 21 percent.

The poll suggests historically fickle New Hampshire voters are beginning to lock in on their preferred candidates. Roughly half, 51 percent, say they are definitely decided, compared to 19 percent who are leaning toward a candidate and 30 percent who are still trying to decide.

Other New Hampshire polls show Buttigieg quickly closing in on Sanders — who carried the state in 2016 over Hillary Clinton, 60 percent to 38 percent— since Iowa, when the two candidates finished neck-and-neck in the still-unresolved caucuses.

While it’s not unusual for a poll like the CNN/UNH survey to be conducted over four days, there is some evidence the race was shifting over the time period, which accounts for half the space between Iowa and New Hampshire. A Boston Globe/WBZ-TV/Suffolk University tracking poll, conducted over the same stretch, gave Sanders a 6-point lead over Buttigieg Tuesday-Wednesday, with Buttigieg nipping Sanders by 1 point Thursday-Friday.

The CNN/University of New Hampshire poll surveyed 365 likely Democratic primary voters and has a margin of error of plus or minus 5.1 percentage points.