Steve Koczela, president of MassInc Polling Group, which conducted the survey for WBUR, said the poll suggests a vigorous cross-party contest for unaffiliated voters will play an important role in the primaries.

The survey suggests that Republicans John Kasich and Jeb Bush would benefit most from a strong independent turnout in the GOP primary, while Democrat Bernie Sanders would get an edge if large numbers of independents voted in the Democratic contest.

About one-third of independent voters in New Hampshire have not decided whether they will vote in the Democratic or Republican presidential primary next month, according to a WBUR poll set for release Thursday morning, injecting an air of uncertainty into the contests.


“There’s voters still looking at both parties’ primaries, and there are candidates competing with every candidate in the race — not just their own party’s,” he said.

WBUR, a Boston public radio station, asked 436 independent voters which primary they planned to vote in, Democratic or Republican. Thirty-eight percent said they were sure they would vote in the GOP contest, while 29 percent said they were sure they would cast ballots in the Democratic primary. The rest of the voters were either undecided, or leaned toward one primary or the other.

The survey collected voters’ candidate preferences, and the pollster analyzed several scenarios.

If every independent voted in the Republican primary, except the 29 percent committed to the Democratic contest, Donald Trump would win 20 percent of independents’ votes, Kasich would take 19 percent, Bush 13 percent, and Ted Cruz 12 percent.

Under a more likely scenario, where half of independents voted in the GOP primary, Trump would win 26 percent of independent voters, Kasich and Cruz 15 percent, and Bush 10 percent.

Another likely scenario has 41 percent of independents voting in the Democratic primary. Sixty percent of those voters would support Bernie Sanders and 33 percent would back Hillary Clinton, according to the survey. Clinton’s support among independents slips when more of them vote in the Democratic primary.


A recent WMUR/CNN poll of likely New Hampshire Democratic primary voters gave Sanders a 27-point lead over Clinton. If the race does not seem competitive come Election Day, said Koczela, independents could flock to the GOP contest, giving moderates like Kasich and Bush an edge.

The WBUR survey of 436 independent voters was conducted Jan. 16-19 and has a margin of error of 4.7 percentage points.

David Scharfenberg can be reached at david.scharfenberg@globe.com. Follow him on Twitter @dscharfGlobe