House Majority Leader Steny Hoyer has picked up another powerful bloc of supporters in his battle to win the Minority Whip job in the next Congress, with seven Democratic chairmen backing his bid.

A letter from the seven backing the Maryland Democrat in his bid against Majority Whip James Clyburn (S.C.) was released early Tuesday, and it includes several liberals close to Speaker Nancy Pelosi (Calif.), a longtime Hoyer rival. Four of the chairmen had not previously made a public declaration of support for either candidate.

“Leader Hoyer is ready to hit the ground running as Democratic Whip,” the chairmen wrote. “He is one of our party’s most effective messengers, with the ability to challenge Republicans on the floor, build support for our party’s middle-class policies across America, and fight back against the special-interest money that played such an important role for Republicans in this election.”

Energy and Commerce Chairman Henry Waxman (Calif.), Financial Services Chairman Barney Frank (Mass.), Foreign Affairs Chairman Howard Berman (Calif.) and Natural Resources Chairman Nick Rahall (W.Va.) made their first public statements for Hoyer in the letter. He already had the public backing of the other three signers — Energy Independence and Global Warming Chairman Ed Markey (Mass.), Intelligence Chairman Silvestre Reyes (Texas), and Veterans Affairs Chairman Bob Filner (Calif.).

“As Committee Chairs, we have worked closely with Leader Hoyer for years,” they added. “We have seen, up close, his inclusive leadership and his strong relationships with Members from across our Caucus.  … Steny Hoyer is a tested leader who can help Democrats rise to the challenge of the next Congress, protect the interests of the middle class, and win back the majority.”

Hoyer has now extended his large lead in declared backers over Clyburn, with 47 in his corner — about half the number needed to win — to 10 for Clyburn, who picked up the backing of Caucus Vice Chairman Xavier Becerra (Calif.) on Monday evening.

Both sides claim many more undeclared supporters.