LAS VEGAS (AP) - Republican incumbent Jon Porter had a 47 percent to 37 percent lead over Democratic challenger Tessa Hafen in the race for Nevada's 3rd Congressional District seat, according to a new statewide poll. Meanwhile, the race for the House seat being vacated by Rep. Jim Gibbons remained too close to call Monday between Republican Secretary of State Dean Heller and Democratic university Regent Jill Derby. Heller drew 45 percent support from the 400 registered voters interviewed, while Derby drew 42 percent. The sampling error margin was plus or minus 5 percentage points, making the Heller-Derby race too...