Hoeffel, vice chairman of the Board of Commissioners, has pledged to run even without his party's backing, which would shake up what are already expected to be bitter campaigns for all three board members.
Republicans, doing some recasting of their own, are expected to shed Board Chairman James R. Matthews from their slate, throwing full support behind the third commissioner, Bruce L. Castor Jr.
Should Hoeffel and Matthews lose their party backing before the primaries, Montgomery County's governing body could undergo its most significant shake-up in recent memory.
"The mark of a mature party is not to run against an established incumbent," said Hoeffel, who seemed surprised that the county Democratic establishment was now speaking so openly against him. "I'm still hopeful we will come together. We need to get our act together."
As a true swing region with active voters and frequent campaign donors, Montgomery County has long drawn statewide political attention.
The commissioners control a budget of $400 million and oversee more than 3,100 employees. But more important, political insiders say, they serve as the public face of their parties on a board considered a launching pad for higher office.
For the last three years, Hoeffel and Matthews have presided over that panel, thanks to an unlikely alliance struck days after the 2007 race.
The election ushered in a high-wattage crew of officials including Castor, a telegenic and outspoken former Montgomery County district attorney; Hoeffel, the face of county Democrats; and Matthews, a three-term incumbent with a bit of celebrity in his own background. His brother is TV cable news host Chris Matthews.
Early on, Hoeffel and Matthews agreed to work together and named Matthews chairman, sidelining Castor, the election's top vote-getter.
