Ayotte, 42, a mother of two and wife of an Iraq War veteran, has run on her background as a tough prosecutor and Granite State mom, but she has been attacked by Binnie and Bender as a hand-picked party insider with questionable ethics and conservative credentials.
Her critics have raised questions about her claim of "victory" in an abortion case brought to the Supreme Court that was actually settled at a cost of $300,000 to taxpayers and her role in a Ponzi scheme case that was insufficiently investigated by her office.
Conservatives also have derided some of what they see as Ayotte's moderate positions on the stimulus, enforcement of immigration law and endorsement of Supreme Court Justice Sonia Sotomayor.
But those hard-hitting attacks, seen largely in a barrage of TV ads among Binnie, Ayotte and Democrat Paul Hodes, have created an opening for Lamontagne, 52, who has managed to remain above the fray.
"Whether you agree with his politics or not, everyone who knows him or meets him likes him," said Andrews, the political scientist. "And he refuses to go negative. He's definitely surging."
Binnie and Ayotte have spent more than $1 million each and have plenty of cash on hand for the final stretch, according to their most recent Federal Election Commission filings. And while Lamontagne has spent about $200,000 so far, aides said, the grassroots contributions are continuing to flow in.
"New Hampshire primary voters are notoriously independent; they don't want to be told by Washington, party bosses or big money people who to vote for," Lamontagne said on "Top Line."
Voters may be only now seriously considering their choice for the nomination, making the next 24 hours a crucial campaign stretch, campaign aides from all four camps said.
"You don't take the voters for granted and try to convince them a year out that, 'this is your only choice,'" a Lamontagne aide said. "New Hampshire always breaks late. Voters take their time, and they're making up their minds right now."