WASHINGTON - Representative Michele Bachmann has rapidly gained ground in a new poll of New Hampshire voters, tapping her popularity with Tea Party activists and potentially causing problems for Republican front-runner Mitt Romney. The former Massachusetts governor, who has long dominated polls in the Granite State, had his lead cut to single-digits in a new survey done by Public Policy Polling. Although polls taken six months before voters head to the polls can be unreliable, they can also provide a window into a volatile Republican electorate. Bachmann, a Minnesota Republican, would get 18 percent of the vote, according to the...