Behind him, there's still a scrum for second place -- with support for No. 2, Texas Sen. Ted Cruz, on the rise.
Trump is backed by 34% of those likely to vote in New Hampshire's February 9 GOP primary, more than double his nearest contender, Cruz, who has 14% support.
Former Florida Gov. Jeb Bush and Florida Sen. Marco Rubio are tied for third with 10% each.
New Jersey Gov. Chris Christie, Ohio Gov. John Kasich and Kentucky Sen. Rand Paul are each tied at 6%, followed by Carly Fiorina with 4% support, Ben Carson at 3% and former Arkansas Gov. Mike Huckabee at 1%.
But the poll's results suggest there's volatility: Just 31% of the Republicans surveyed say they've made up their minds about who they'll support.
Cruz is the candidate who has grown the most since a December poll: He's climbed from 6% to 14%, largely on the strength of a favorability rating that has jumped from 46% in December to 55% now.
Trump, though, dominates on the two issues that likely voters have identified as most important: the economy and the threat of ISIS.
Nearly half -- 48% -- of Republicans say Trump would best handle the economy, far ahead of Bush, Cruz and Kasich, with just 7% each. And 32% say he'd best handle ISIS, ahead of Cruz's 14%, Bush's 12% and Rubio's 10%.
The poll carries both good and bad news for Bush: He's cracked double-digit support for the first time since last summer. But he is viewed unfavorably by 51% of the state's Republican voters, with 40% viewing him favorably.
The survey of 413 likely New Hampshire Republican primary voters was conducted January 13-18 by the University of New Hampshire Survey Center. Its margin of error is plus or minus 4.8 percentage points.