In another potential blow to Michael Steele’s chances for a second term, a once-close Steele ally and chief counsel to the RNC has resigned, a move that could signal a potential run for the chairmanship:

Reince Priebus, the Republican National Committee’s top legal counsel, resigned his position early Sunday morning, The Hotline has learned, a move that will be widely interpreted as a major step toward running for chairman of the organization and a big blow to current chairman Michael Steele.
Priebus, the chairman of the Wisconsin Republican Party, was once Steele’s closest ally on the committee. Priebus pushed to elect Steele in 2009, and in the two years since has served as Steele’s conduit with committee members.
“In a private letter to Chairman Steele, I did resign today as General Counsel. I appreciated the opportunity to work with all of the members that make the RNC so special,” Priebus confirmed in an email to The Hotline.
Priebus spent his term in office running interference for Steele, organizing letters of support for the chairman at crucial moments when other committee members actively considered calling for Steele’s resignation. Sources close to Priebus said he had grown increasingly uncomfortable with those duties, and with Steele’s time in office. He has been encouraged by other RNC members, including others once close to Steele, to run for national chairman himself.
Priebus has said he is considering a bid, and he is likely to make his decision public some time this week. But quitting his post is a strong indication he is likely to run for chairman, whether or not his one-time ally seeks a second term.

More here.

UPDATE: Sure enough:

Reince Priebus, chairman of the Republican Party of Wisconsin and member of the Republican National Committee, has formed a 527 to support his bid for chairman of the RNC.
Priebus’ bid is a blow to chairman Michael Steele, who hasn’t announced whether he will run for re-election. Priebus promoted Steele’s bid for chairman in 2009 and remained an ally during Steele’s rocky tenure.
Priebus stepped down from his position as counsel for the RNC over the weekend, and he sent a letter Monday announcing his bid to members of the RNC, according to Hotline On Call.
“The RNC must be at its best during this next election cycle,” he wrote. “There is too much at risk for our Party and, more importantly, for our country. That is why I am running for Chairman.”