He didn't name either of his rivals, but he pointed to job growth in Texas and argued that Republicans needed a candidate who has achieved results.
Bachmann, for her part, prepared for a bus tour that starts Tuesday in South Carolina, a state set to hold the first primary in the South.
Since declaring her candidacy, she has shot to the top tier in GOP polling, has largely avoided mistakes, has logged two solid debate performances and has established herself as a far more serious candidate than her rivals had predicted. She's worked to broaden her appeal beyond the tea party and evangelical wings of the party.
She earned a widely publicized boost on Saturday, winning 4,823 votes, or 28 percent, of the die-hard activists who set aside a Saturday afternoon every four years for a political carnival at Iowa State University's campus in Ames.
The man they all hope to replace wasn't taking it sitting down.
In little Cannon Falls, Minn., Obama told audience members hard hit by the difficult economy, "As frustrated as you are about politics, don't buy into this notion that somehow government is what's holding us back." He noted that the government is responsible for the military that defends the nation and for many other programs people embrace. He said, "When you go to the National Parks and those folks in the hats, that's government."
A fellow Democrat, former President Bill Clinton, had something to say about the GOP's latest entrant. Perry is a "good looking rascal," Clinton allowed in New York, but he indicated he doesn't think much of the Texan's policies.
Both of Romney's freshly minted rivals face challenges.
Neither has run a national race, and both still are relatively unknown to the broad public.
By contrast, Romney is known nationally from his failed 2008 presidential bid and has been through the paces of a White House bid. He also is a known quantity in Iowa; he won the state's straw poll in 2007 before coming up short in the 2008 caucuses. Yet he didn't actively compete in Saturday's test vote in Ames and earned fewer votes than Perry, whose supporters wrote him in.
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