'Dingell has a strong record of accomplishment for the first two years back in the majority and is positioned to move full speed ahead with an aggressive agenda on climate change, healthcare reform, and food and drug safety in the 111th Congress,' Seth said. 'Dingell has proven that he is the best person for this job. This is unhealthy, and does not benefit the party in any way.' She said the move wasn't helpful. 'Tearing a leadership apart is something the Republicans should be doing after their big loss, it shouldn't be the first order of business for the Democrats after a historic election,' she said. Karen Lightfood, a spokesman for Waxman, didn't immediately return a call seeking comment. Waxman has favored tough regulations on automakers, including much higher fuel efficiency standards and allowing California and at least 13 states to impose their own vehicle emissions limits. Those states were denied a waiver under the Clean Air Act by the Environmental Protection Agency last year that would have allowed them to impose the stricter limits. Dingell has strongly backed automakers opposition to the state emissions standards, but he helped broker a deal to boost efficiency standards by 40 percent by 2020 to a fleet-wide average of 35 mpg that became law in December 2007. Waxman is a close ally of House Speaker Nancy Pelosi, D-Calif. But Waxman, who is currently a member of the House Energy and Commerce Committee, also backed Dingell in January 2007 when she created a select committee on Energy Independence. Waxman sought to preserve the jurisdiction of the Commerce Committee. Waxman called Dingell this morning to tell him of his decision to challenge him, aides said. Waxman, who is chairman of the House Oversight Committee, and Dingell, are both calling members trying to line up their support. The committee once had a picture of the earth on the wall, which symbolized -- aides joke -- the vast jurisdiction. The House passed nearly 100 bills under Dingell's committee last year and held 174 hearings. You can reach David Shepardson at (202) 662 - 8735 or dshepardsondteom.