And don't expect Romney's rivals to stop at the economy when criticizing him during Tuesday night's debate at Dartmouth College. With time running out before the first votes are cast in the GOP nominating process, the race is quickly becoming a scattershot effort to deny Romney the nomination by any means necessary.
"Even the richest man can't buy back his past," Texas Gov. Rick Perry's campaign said in a web video that describes Romney as the inspiration for President Barack Obama's national health care overhaul.
Rep. Michele Bachmann of Minnesota urged conservative voters not to support a candidate who isn't one of them. "It's not good enough to settle for anyone but Barack Obama," she said while campaigning in New Hampshire on Monday.
Even lower-profile rivals tried to knock Romney off his game.
"Simply advocating more ships, more troops and more weapons is not a viable path forward," former Utah Gov. Jon Huntsman said in a foreign policy speech that was a direct rebuttal to Romney's a week earlier.
Romney's rivals readied criticism on health care policy, cultural issues and environmental positions. Even with a focus on the economy and voters most concerned about 9.1 percent unemployment, there was scant chance Romney would be able to dodge questions about his overall record.
"For some people in campaigns their process is one of obfuscation and bewilderment," Romney said Monday when he visited a VFW hall.
"You're going to find in a campaign like this people running against me who will take what I said and try to say something else. There's an ad out there today that does that," he said, referencing Perry's ad, which interspersed images of Romney and Obama talking about health care.
Both Perry and Bachmann have tried to pitch themselves as an alternative to Romney, who as Massachusetts governor signed into law a health care mandate that conservatives loathe.
However, those candidates also stumbled in their early attempts: Perry flubbed a practiced criticism during his last debate, and Bachmann struggled to maintain her fast rise in popularity and gain traction for her message casting Romney as a moderate who can't be trusted.
Such criticism has not broken Romney's pace. Nothing, to this point, has sparked an exodus among his supporters.
While New Hampshire has yet to schedule its primary, it is likely to come before mid-January. That means there are fewer than 100 days for the newcomers to make inroads in a state where Romney is well known, owns a vacation home and won a second-place finish in his 2008 presidential bid.
Yet, his rivals note, Romney hasn't faced steady, nasty attacks here on television. His chief opponent four years ago, Sen. John McCain, didn't have the campaign cash to buy the commercials.
That is not the case now. Perry is sitting on $15 million. Bachmann has yet to report her fundraising, but previous campaigns show she is a prodigious fundraiser who isn't shy about spending. And Huntsman, who has made New Hampshire his make-or-break state, has a personal fortune he could tap; his allies have established an independent organization that could run anti-Romney ads.
Perry's campaign signaled that its anti-Romney ads were almost certain to start soon.
At the ready is a strong defense of Romney, emphasizing his record as a business executive whose campaign has been based almost exclusively on the economy. Since coming up short four years ago, he and his advisers have laid the extensive groundwork to respond quickly with a message tailored to the economic uncertainty.
If the decision of voters comes down to the economy, Romney is ready to highlight his accomplishments -- and his rivals' shortcomings.