Majority Leader Steny H. Hoyer (D-Md.) has intervened in the fight between Reps. John Dingell (D-Mich.) and Henry A. Waxman (D-Calif.), hoping to resolve their battle over the chairmanship of the powerful Energy and Commerce Committee, one senior Democratic aide confirmed on Wednesday. But neither combatant has agreed to a deal and the dispute may still be resolved by a secret ballot next week.