LACONIA, New Hampshire — Former House speaker Newt Gingrich hammered Mitt Romney Wednesday, saying only a "Reagan conservative" like himself can unite Republicans to beat President Barack Obama in November.

One day after a lackluster performance in the Iowa caucuses, won narrowly by Romney, Gingrich placed a full-page ad in New Hampshire's Union-Leader newspaper, comparing his and Romney's positions on taxes, abortion and guns.

Romney, the former Massachusetts governor, has a wide lead in the polls in New Hampshire, which will stage its primary on January 10.

Gingrich, who blamed attack ads by Romney and surrogates for his poor fourth-place finish in Iowa, will soon put up a TV ad attacking Romney in New Hampshire, South Carolina and Florida.

"The key to this race this week is the clear contrast between a Reagan conservative and a Massachusetts moderate," Gingrich told reporters after a town hall meeting where he also outlined his differences with Romney.

"I am a person who has twice helped change Washington, once with (President Ronald) Reagan and once as speaker. He's a person who accommodated liberalism in Massachusetts."

"There's no evidence he changed Massachusetts," Gingrich said, noting that while he had worked to cut taxes, Romney had raised taxes as governor.

"He went in and created bigger government, more bureaucracy and was sort of a normal Massachusetts governor."

Gingrich is in third place in New Hampshire, with nine percent support among likely voters in the Republican primary, according to a two-day tracking poll by Suffolk University/7News.

Romney leads, at 43 percent, followed by veteran Texas congressman Ron Paul, at 14 percent. Only 16 percent of likely Republican primary voters say they are undecided.

Gingrich, who has little money or ground game in New Hampshire compared to Romney, ducked a question about how he could raise enough money to mount an effective TV ad campaign against Romney here and in later contests.

Instead, he stressed his view that Romney -- who only beat Christian conservative Rick Santorum by eight votes in Iowa -- is highly vulnerable and has not been able to rally the party's conservative base.

"Only an effective, articulate conservative can defeat Barack Obama," Gingrich said.

Gingrich said the idea that Romney is electable is "silly," though he admitted he would be willing to endorse Romney if he becomes the Republican nominee.

Gingrich is running on his record as House speaker from 1995-1999, when he worked to balance the budget, cut taxes and overhaul welfare.

"I am the only candidate in this race who has an actual track record of having changed things in Washington," Gingrich told voters at the town hall.

He wants to set zero taxes on capital gains, lower the corporate tax rate from 35 percent to 12.5 percent, give taxpayers a 15-percent flat tax option and tie unemployment benefits to job training.

Pollster Andrew Smith of the University of New Hampshire doubts Gingrich can deliver a knock-out punch to Romney in the Granite State.

"Gingrich has lost his momentum," said Smith.

"It's tough to get it back. None of the earlier Republicans who lost their momentum were able to regain it. And it's especially hard for him now with Rick Santorum rising as the anti-Romney."

Gingrich will need more supporters like 72-year-old retiree Janet Moorhead, who said Gingrich had her vote because the country needs a "cage-rattler."

"We need someone to go to Washington and shake things up. That's the only way things are going to get things done," Moorhead said.