Argument over the best way to reform oversight of Fannie Mae and Freddie Mac is set to begin as Republican leaders in the Senate introduced a bill this week that should spur heated debate this session. The proposal was submitted Wednesday afternoon and had not been given a number as of press time, Senate staffers said. It was introduced by GOP Senators Chuck Hagel, NE, John Sununu, NH, and Elizabeth Dole, NC, who put forward…