Updated: 12:43 p.m.

Rep. Henry Waxman (Calif.) has ousted Energy and Commerce Chairman John Dingell (Mich.), as Democratic lawmakers voted 137-122 on Thursday morning to hand the gavel of the powerhouse panel to its second-ranking member.

The vote marks a stunning rebuke of the seniority system that Democrats have honored for decades. It also constitutes a win, of sorts, for Speaker Nancy Pelosi (D-Calif.), who is ideologically aligned with Waxman and has clashed repeatedly with Dingell. Though Pelosi steered clear of any involvement in the race herself, Rep. George Miller (D-Calif.), one of her top lieutenants, helped lead the charge for Waxman.

The relatively wide margin appeared to surprise lawmakers lined up on both sides of the contest. Many Dingell backers streaming out of the Cannon House Office Building Caucus Room shortly before 11 a.m. appeared shaken by the resounding defeat that their colleagues had just handed the dean of House.

“I can’t believe we just did what we did,” said Rep. Stephanie Herseth-Sandlin (D-S.D.), a whip for Dingell.

The result raised questions about the status of other long-serving chairmen, Dingell’s fellow Old Bulls, who have already seen their power eroded as Pelosi repeatedly seized the initiative from them over the last two years.

It was a fact not lost on the chairmen themselves, most of whom lined up behind Dingell. Asked about the seniority system in the wake of Dingell’s toppling, Ways and Means Chairman Charlie Rangel (D-N.Y.) said, “It has just been buried.”

But Rep. Jim Cooper (D-Tenn.), who broke with fellow senior members of the Blue Dog Coalition to back Waxman, said the seniority argument had been overblown. “It’s an argument of convenience, like states rights. Nobody really believes it,” he said. “We don’t own these jobs. These jobs are a gift from the Caucus. Dingell is one of the all-time greats, but that doesn’t mean you get 30 years. He got 28 years.”

Cooper said the contest “boiled down to, ‘Do you want the best quarterback or the oldest quarterback?’”

The contest also split the Caucus along ideological lines, with most liberals appearing to line up behind Waxman while moderates rallied to Dingell. For moderates, the Dingell defeat compounded what they view as an alarming leftward shift in the Caucus, set in motion in the days after the election as Pelosi moved to help her loyalists lock up leadership posts. “The whole movement is to the left,” said one moderate Democrat leaving the vote Thursday morning.

The centrist wing of the party has been quietly arguing they deserve better treatment, especially considering that Democrats from conservative districts have delivered the party its expanded margin in the House.

It remains to be seen whether they will make an outright demand for a new leadership slot, or some other formal recognition from the Speaker. “It’s going to take a little while to step back and figure it out,” the lawmaker said.

What’s next for Dingell was not immediately clear, either. One option for him would be to take the gavel of the Energy and Commerce Subcommittee on Health, a reduced though still significant portfolio as lawmakers gear up for an expected health care overhaul.

After the vote, Pelosi announced that Dingell will continue to serve the on panel as chairman emeritus, a post with unclear duties but that represents an olive branch to the fallen gavel-holder.