A Texas natural gas magnate last month gave $1 million to American Crossroads, a new 527 group conceived by Karl Rove and Ed Gillespie to boost Republicans headed into the 2010 midterm elections. The contribution, from Trevor Rees-Jones, president of Chief Oil and Gas, a privately held energy company in Dallas, was the only significant contribution made in April to the new group, according to a report it filed Thursday with the Internal Revenue Service.