An unrelenting President Barack Obama jabbed at Mitt Romney's record with a private equity firm in an ad Saturday that aimed to keep his rival on the defensive just as the Republican challenger's campaign hoped to take advantage of poor economic data to gain an edge on the incumbent. Obama met Romney's plea for an apology for the attacks with a mocking ad that charged that the firm shipped American jobs to China and Mexico, that Romney has personal wealth in investments in Switzerland, Bermuda and the Cayman Islands, and that as Massachusetts governor, he sent state jobs to India....
