A freshman state legislator joined a Republican field seeking a U.S. Senate seat Thursday, setting his sights on a robust Minnesota network for presidential candidate Ron Paul as a possible route to the party nomination. State Rep. Kurt Bills announced his campaign on a busy intersection in Rosemount, just up the street from a high school where he teaches an early morning economics course before heading to the state Capitol each day. The former city council member said he'd make the nation's debt and deficit the focus of his campaign, though he wouldn't offer hints of how he'd solve it....