Four in 10 Republicans in New Hampshire want a candidate to challenge President Trump in the 2020 primary, according to a new poll.

The poll by the New Hampshire Journal found that a majority of voters surveyed believe a GOP primary challenge for the president "would be a good thing." Fifty-six percent of respondents overall supported a challenge, while 40 percent of Republicans did.

Forty-seven percent of GOP New Hampshire voters surveyed said a GOP opponent would be a "bad thing."

New Hampshire hosts the first presidential primary in the U.S., and it is a traditional testing ground for Republican and Democratic presidential nominees.

"The fact that 40 percent of Republicans in an early and influential state like New Hampshire think a Trump primary challenge would be 'a good thing' should get the GOP's attention," said the Journal's politics editor Michael Graham. "The fact that nearly 60 percent of unaffiliated voters - all of whom can also vote in the 2020 primary-agree raises the stakes even higher."

The Granite State has often supported primary challenges to sitting presidents.

Trump's approval rating among Republicans in New Hampshire is at least 10 points lower than his average among Republicans nationwide at 72 percent. His approval rating overall is 41 percent, similar to the national average.

Fifty percent of voters in the poll said they are not likely to vote for Trump in 2020 and 36 percent responded they are "very likely" to vote for him.

The poll, conducted by Praecones Analytica, surveyed 626 registered voters between Aug. 13-15 with a margin of error of 3.9 percent.