WOLFEBORO, N.H. — Mitt Romney is planning to fortify his communications and messaging team by adding seasoned operatives, advisers close to the campaign said Thursday, after withering criticism from prominent conservative voices that his insular team has fumbled recent opportunities. Romney’s advisers insisted that he would keep his inner circle intact amid growing concerns about the Republican presidential candidate and his campaign. The tempest began with a weekend tweet from media tycoon Rupert Murdoch and burst Thursday onto the pages of his newspaper the Wall Street Journal, as its conservative editorial board opined that Romney’s advisers were “slowly squandering an...