Minority Whip Steny Hoyer (D-Md.) is privately backing Pallone, meaning Pelosi and her top lieutenant and onetime rival find themselves once again on opposite sides in a leadership fight.

In a letter to her Democratic colleagues on Thursday, Pelosi wrote that she will “strongly endorse Anna Eshoo to become the top Democrat on the Energy and Commerce Committee. It had not been my intention to make a public endorsement, but so many of you have asked, I am writing to let you know that I support Anna.”

Pelosi added: “Her proven leadership as Ranking Member on the Communications and Technology Subcommittee and the eight years she spent on the Intelligence Committee give Anna the understanding of the balance between security and liberty, which serve our caucus and the Congress well.”

Pallone did not directly address Pelosi’s endorsement of Eshoo, and he shows no sign of backing away from the race, despite Pelosi’s overwhelming strength within the Democratic Caucus.

“Congressman Pallone has been energized by the encouragement of many of his colleagues and looks forward to continuing to discuss his record and vision of the future of the Energy and Commerce Committee,” said Ray Zaccaro, Pallone’s communications director. ”As the senior Democrat on the Health Subcommittee, Congressman Pallone has either chaired or served as ranking member of three of the Committee’s six subcommittees and his seniority and experience have been widely viewed as great assets by many in the Democratic Caucus.”

Rep. Henry Waxman (D-Calif.), current ranking member on Energy and Commerce and a Pelosi ally, is retiring at the end of this Congress. Rep. John Dingell (D-Mich.), the legendary former chairman of the panel during its heyday, also announced this week that he will retire.

Eshoo was first elected to the House in 1992, while Pallone has been a lawmaker since 1988.

But there are several other ranking Democrats who are also not the most senior members of the panel beyond Waxman. These include Rep. Elijah Cummings (D-Md.), ranking member on Oversight and Government Reform, as well as Rep. Nita Lowey (D-N.Y.), ranking member on the Appropriations Committee.

Despite Pelosi’s support, Pallone may have the upper hand in his fight with Eshoo. He is getting strong support from the ranks of the Congressional Black Caucus and Congressional Hispanic Caucus, who lean toward Pallone based on seniority. That’s a key issue for both factions, and some senior Democrats were unhappy with Pelosi’s open support for Eshoo.

“I heard that [Pelosi] buried the concept of seniority,” complained Rep. Charlie Rangel (D-N.Y.). “Officially buried it.”

Pallone is also doing well with freshmen Democrats, although Pelosi’s involvement could have an impact there.

Some Democrats, though, question Pallone’s commitment to the House Democratic Caucus, as Pallone was long considered a potential Senate candidate. Pallone just recently paid his $250,000 dues to the Democratic Congressional Campaign Committee, while Eshoo has already paid her $250,000.

Eshoo, however, has raised more than $817,000 for the DCCC, according to the most recent dues sheet. Pallone has raised $364,000.