He helmed Montgomery County government for the last three years without the backing of his party. But Republican Commissioners Chairman James R. Matthews said this week he won't run for re-election without it.

In an interview Tuesday, Matthews said he would call it quits at the end of this year unless the county GOP opted to draft him for their 2011 ticket - a prospect even he conceded looked increasingly small.

The decision reverses his earlier vows promising a bid for a fourth term with or without party support just to stymie the election chances of his avowed political enemy fellow Republican Commissioner Bruce L. Castor Jr.

"I have a great legacy," Matthews said. "I'm satisfied with my 12 years in office. I'm not going to taint that with an independent run."

Matthews' departure from the crowded GOP field clears at least one headache for a party that appears increasingly fractured heading into this year's primary race.

Although party insiders said Matthews, 52, had little chance of securing a GOP nomination, had he launched an independent run he could have siphoned off hundreds of loyal Republican votes and perhaps tipped the advantage to the Democrats in a general election.

Such an outcome, though, would only have earned him more animosity among members of the county's Republican committee, many of whom never forgave him for his 2007 power sharing deal struck with Joseph M. Hoeffel III, the lone Democrat on the three-man board of commissioners.

The pact - which effectively sidelined Castor and Republican dominance of the board - led to years of acrimony at the top of county government and open hostility between the GOP's top two men.

As recently as Monday, Matthews told several media outlets that he would run in the primary solely to frustrate Castor's chances of taking over the county board.

Later that evening, though, he had changed his mind. Driving to Harrisburg to participate in Gov. Tom Corbett's inauguration ceremonies, he started to think of the message such a move would send to Republicans across the state, he said.

"I'm thinking, 'I'm going up here to meet hundreds of people I know who respect me at the state level, and here I am talking about running against my own party,' " he said. "That's not me. That's not Jim Matthews."

A Navy veteran, Matthews got his start in government working for Philadelphia's scandal-ridden Democratic machine in the early 1970s. He moved to Montgomery County in 1973, became a Republican, and founded Keegan Mortgage, a company named after his father-in-law, 16 years later.

His 1999 race for the county board of commissioners landed him his first elected seat and the office he still holds today. Of his three terms in office, he spent two as the chairman of the board. He also ran in 2006 as the Republican Party's nominee for lieutenant governor, on a ticket helmed by Lynn Swann.

But controversy plagued him in the latter half of his tenure. Aside from hostile relations with Castor, a Montgomery County grand jury continues to probe several breakfast meetings he had with Hoeffel that may have violated the state's Sunshine statute. Others have questioned his spending of campaign contributions on car rentals and his relationships to many county contractors.

Hoeffel, who said Tuesday he had not been advised of Matthews' decision to bow out, praised his ally's legacy as a consensus builder, even if it was what ultimately led to his downfall.

"The fact is, Jim was able to lead a government to bipartisan success," he said. "It was his undoing as a politician, but it's his greatest success as a public servant."

Castor, meanwhile, has made no secret of his disdain for his colleague but responded to the news with a rare tip of the hat. During his first term, he said, Matthews made significant strides in reducing the county's debts, increasing its reserves and slimming public payrolls.

Still, Castor couldn't avoid taking a final jab at his rival: "Nobody remembers Benedict Arnold was once a heroic general. Everyone remembers him as a traitor," Castor said. "Jim Matthews did everything he could for the county early on, but his legacy is going to be that of a traitor."

Once he leaves office next year, Matthews said he hopes to remain active in county and statewide politics, focus on his mortgage business, and pursue a possible job with Corbett's administration.

"I think the county party is in a very fragile position right now," he said. "A lot of good people have been chased away by leaders with the wrong priorities. There's a lot of freedom in being a free agent."

Contact staff writer Jeremy Roebuck at 610-313-8212 or jroebuck@phillynews.com.