"I think he [Trump] is an unmitigated disaster for the Republicans," Jasper said on Tuesday.
If Trump does not turn out a victory in New Hampshire with a significant double-digit spread, "I think it dramatically changes the prospects [of a Trump victory] going forward."
On Tuesday, New Hampshire is holding presidential primaries and Secretary of State Bill Gardner has estimated voter turnout will be around 550,000 people.
Jasper, a Republican who took leadership in the New Hampshire statehouse in 2014, noted that in his 36 years in politics "I have never heard so many people in my political life… say I will not vote for him [Trump] no matter what. I just won’t vote for president."
The polls in New Hampshire will close by 8 p.m. EST (12:00 a.m. GMT), with early results expected well before midnight.
The primary election allows voters to decide the candidate to represent the Republican and Democratic parties in the general election this coming November.
