A packed field of candidates including Bush, Rubio and Carson are close behind.
Most Iowa voters wouldn’t mind an ex-president playing a prominent role in the White House.
The governor poses the most formidable challenge to Ayotte's reelection efforts.
The survey was conducted on behalf of conservative super-PAC American Crossroads.
Sixty-eight of people in New Jersey said the charges against him should be settled first.
Bush, Rubio, Walker and Paul are all within 5 percentage points in the survey.
Huckabee, Rubio and Paul perform best in head-to-head match-ups with Clinton.
Clinton leads Walker 52 percent to 40 percent in a hypothetical 2016 matchup in Wisconsin.
A new poll finds Clinton winning every head-to-head GOP match-up by double digits.
Eighty-six percent of Democrats could support her for president, according to new poll.