Bloomberg Businessweek: Rivals of Mitt Romney in the Republican presidential race zeroed in on the former Massachusetts governor today, hoping to halt the front-runner's momentum ahead of New Hampshire's pivotal Jan. 10 primary. Former U.S. House Speaker Newt Gingrich, wounded by a fourth-place finish in yesterday's Iowa caucuses, attacked a cornerstone of Romney's candidacy: that he is best positioned to defeat President Barack Obama in November's general election.