It started innocently when Romney said insurance companies should serve their clients.
"If someone doesn't give me the good service I need, I want to I'm going to go get somebody else to provide that service to me," he said.
His rivals were quick to use the firing statement against him.
"It seems that Gov. Romney believes in putting politics first. Gov. Romney enjoys firing people. I enjoy creating jobs," said Jon Huntsman, who was tied for third in the WMUR polls with Rick Santorum, both second to Ron Paul.
Republicans still have their doubts about Romney.
Those doubts were on display in Dixville Notch, the tiny New Hampshire village that traditionally votes at midnight. Romney and Huntsman each received two of the six votes cast; Newt Gingrich and Paul received a vote apiece.
The rest of New Hampshire voters go to the polls Tuesday after receiving months of attention from the Republican candidates and witnessing an increasingly sharp tone in the intraparty struggle for the nomination.
Santorum toured a diner in Derry on Monday, mobbed by dozens of reporters and cameras.
Ask if he'd be satisfied with a second place finish, Santorum said, "I'd be ecstatic with a second place (finish), are you kidding me? ? Ron Paul has run here about 17 times. To do as well as him, I'm not sure that's possible."
Paul also attracted a mob of media, about 50 cameras and 100 reporters, while campaigning at Moe Joe's Restaurant in Manchester
That latest poll has former House Speaker Gingrich in fifth place. During a news conference, Gingrich accused Romney of closing companies to make a profit and subsequently hurting workers.
"I do draw a distinction between looting a company, leaving behind broken families and broken neighborhoods and leaving behind a factory that should be there," Gingrich said.
The GOP candidates who are contesting the state have generall been content to vie for second place in hopes of emerging as his main rival in the South Carolina primary on Jan. 21.
Romney, the former Massachusetts governor, won in Iowa by eight votes. A victory in New Hampshire would make him the first Republican in a contested presidential nomination battle to capture the first two races of the campaign since Iowa began leading off for the GOP in 1976.
The Associated Press contributed to this report.