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Charlie Riedel, Associated Press
Republican presidential candidate former House Speaker Newt Gingrich, with his wife Callista, speaks at a Hy-Vee store in Mt. Pleasant, Iowa, Tuesday, Dec. 20, 2011.

BEDFORD, N.H. — Sharpening his message ahead of voting in Iowa and New Hampshire, Republican presidential hopeful Mitt Romney on Tuesday attacked President Barack Obama as Newt Gingrich, his chief rival, accused Romney of running a "negative smear campaign" in the GOP primary.

"We will not surrender our dreams to the failures of this president. We are bigger than the misguided policies and weak leadership of one man. America is bigger than President Obama's failures," Romney said. "This America of long unemployment lines and small dreams is not the America you and I love. ... These troubled years are President Obama's legacy, but they are not our future."

Romney's allies escalated their negative ad campaign against Gingrich on Iowa airwaves as Romney accused Obama of deepening the economic crisis and backing policies that will redistribute wealth instead of creating equal opportunity for people to do well.

Romney, a former businessman, told voters in an evening speech that his policies would turn the U.S. into an "opportunity society" while Obama's vision for an "entitlement society" would make more people dependent on government welfare.

Romney said that Obama "believes that government should create equal outcomes. In an entitlement society, everyone receives the same or similar rewards, regardless of education, effort and willingness to take risk."

Romney's message contrasts with the argument the Democratic president has begun to articulate for his re-election, in which he calls for a society that offers "fair play, a fair shot and a fair share." Obama argues that Republicans put the interests of the wealthy above the middle class.

"Giving more handouts to millionaires, billionaires and large corporations and making the middle class foot the bill are the same flawed policies that led to the economic crisis in the first place," Obama campaign manager Jim Messina told New Hampshire reporters.

Restore Our Future, a special political action committee, or "super PAC," that backs Romney, launched a caustic ad tying Gingrich to Freddie Mac, the quasi-government mortgage company, and House Democratic leader Nancy Pelosi. The spot also hits Gingrich for ethics violations and criticizes his record on abortion.

In Iowa, Gingrich accused Romney of allowing the super PAC to fuel a "negative smear campaign" and called on Romney to demand that ads run on his behalf by such groups be positive. Gingrich said Romney's comments aimed at distancing himself from the anti-Gingrich ads were misleading and false.

"Understand, these are his people running his ads, doing his dirty work while he pretends to be above it," Gingrich told reporters after a campaign appearance at a heavy machinery plant in Ottumwa, Iowa. "I don't object to being outspent. I object to lies. I object to negative smear campaigns."

During his remarks to about 100 people at the Al-Jon Manufacturing plant in eastern Iowa, one voter asked Gingrich about a political mailing he had received describing the former congressman as a globalist.

"I think these guys hire consultants who get drunk, sit around and write stupid ads," Gingrich replied. "Every one of these candidates should take responsibility for the lies they are putting up." He offered no evidence for his assertions.

Gingrich has pledged to remain "relentlessly positive" as he campaigns for the nomination and said Tuesday that he wasn't violating that promise but simply correcting the record.

Romney refused earlier Tuesday to disavow the group's ads, saying it would be illegal for him to coordinate with the super PAC. He did say that such groups are a "disaster" and have made a "mockery" of the presidential campaign.

"I'm not allowed to communicate with a super PAC in any way, shape or form," Romney said. "If we coordinate in any way whatsoever, we go to the big house."

Gingrich read Romney's remarks to reporters and then promptly labeled them "baloney." He again urged Romney to demand that the negative spots be taken down.

A 2010 Supreme Court decision paved the way for such groups to accept unlimited amounts of money from donors. The political campaigns are limited to accepting $2,500 per donor.

Gingrich said Restore Our Future was created by Romney's former staff and funded "by his friends' personal wealth."

Gingrich's own former top aide, Rick Tyler, has joined a pro-Gingrich PAC called Winning Our Future. The former House speaker said he would expect the PAC to adhere to his positive strategy.

"If Rick Tyler runs a single negative ad, I will disown the PAC and discourage anyone from giving them a penny," Gingrich said.

Gingrich has seen his candidacy slide in polls as a barrage of ads attacking him blanket the Iowa airwaves in advance of the state's first-in-the-nation caucuses Jan. 3. He has been trying to counter the assault while still maintaining a positive campaign.

Romney, the former governor of Massachusetts, didn't mention Gingrich during his speech. He was using the address to open four straight days of campaigning in New Hampshire, which holds the nation's first primary on Jan. 10. He must win the state if he hopes to become the Republican nominee.

Two weeks remain until voting begins Jan. 3 with the leadoff caucuses in Iowa, though Romney will campaign in New Hampshire through Christmas in a sign of the state's importance to his political strategy.