House Judiciary Chairman John Conyers (D-Mich.) is throwing his support behind his home-state colleague, Energy and Commerce Chairman John Dingell (D), in the fight for control of Energy panel’s gavel, a Conyers spokesman confirmed.

Dingell is trying to fend of a surprise challenge that Rep. Henry Waxman (D-Calif.), the No. 2 Democrat on panel, launched last week.

Conyers’ support should come as no surprise. Dingell’s fellow chairmen have a vested interest in protecting the tradition of seniority, lest they face challenges for their own gavels. And the two Michigan Democrats have been working together in recent days to win support for a federal bailout of the sputtering auto industry.

But Conyers also is a liberal, an allegiance that could have made him amenable to an appeal by Waxman, a stalwart of the party’s left wing. Rep. Carolyn Cheeks Kilpatrick — who, like Conyers, is a liberal Detroit Democrat — is still undecided in the contest, her spokeswoman said Wednesday.

The Conyers endorsement gives Dingell a decided edge over Waxman among committee chairmen. Dingell already has the support of Ways and Means Chairman Charles Rangel (D-N.Y.), Agriculture Chairman Colin Peterson (D-Minn.), Science and Technology Chairman Bart Gordon (D-Tenn.), and Gene Green (D-Texas), chairman of the Committee on Standards of Official Conduct.

Waxman, who chairs the Oversight and Government Reform Committee, is getting help rounding up support from two fellow chairmen from California: Foreign Affairs Chairman Howard Berman and Education and Labor Chairman George Miller.

Waxman has not made the names of his supporters public.