Montgomery County Commissioner Jim Matthews, a Republican, and newly elected Commissioner Joe Hoeffel, a Democrat, are expected to announce a deal this morning to share some of the power at the county courthouse in a move that will undercut incoming Republican Commissioner Bruce L. Castor Jr.

Under the plan, Matthews would become chairman of the Board of Commissioners and Hoeffel would become vice chairman, according to a Democratic strategist. Though Republicans would retain most top positions in county government, Democrats would be placed in second-rank positions in some offices.

"Full inclusion" is how one long-term GOP official described it last night.

The unusual alliance stems from the troubled relationship between Matthews and Castor, who gave up his job as district attorney to run for commissioner.

"They can't stand each other," said one official, speaking on condition of anonymity. "Neither wants the other to be chairman."

Castor disagreed. "I like Jim Matthews, and if he wants to be chairman, there are a number of circumstances in which I would agree to support him," he said last night.

An alliance between a Republican and Democrat would give the Democrats real power in the county courthouse after failing to win control at the ballot box in November.

Hoeffel, a former congressman, confirmed late yesterday that he and Matthews would hold a news conference this morning in Norristown "to announce our plans for the future of the county government."

"We're going to focus on the government side of things, not the politics, and move forward," said Hoeffel, who declined to comment further.

In November, Matthews won reelection and Castor and Hoeffel were elected to the two other seats on the board. A second Democrat on the ballot was defeated, allowing the GOP to keep control.

During the campaign, Matthews and Hoeffel clashed with Castor, with Hoeffel calling him "Bruce Almighty" and Matthews saying Castor's ego was so big, "it could float the Titanic."

In an e-mail to Matthews yesterday, Castor noted the "many wild rumors flying around" and asked for a meeting.

"It has been my position all along that the committee and the voters chose a Republican majority," Castor wrote. "We simply must implement their wishes. To that end, we both have repeatedly pledged that under no circumstances would either of us agree to any reorganization issue with support only from Joe Hoeffel.

"I take that pledge very seriously," Castor wrote. "So I ask you outright: Can we agree that neither of us will make a deal with Hoeffel on anything?"

In an interview, Castor described his relationship with Matthews as "cordial" and said "no good Republican" would hand over power to a Democrat, especially at the expense of a fellow Republican.

"I can't believe that will happen," Castor said.

During the campaign, Hoeffel attacked Matthews for accepting financial support from Republican National Committee member Bob Asher, a Matthews ally.

Asher was convicted in a 1986 bribery-related case. There is a long-standing rift in the county GOP between pro-Asher and anti-Asher factions. Castor is a member of the latter group.

But Asher, a philanthropist and major financial backer of former Gov. Tom Ridge and President Bush, is beloved by both sides of the state's political establishment, and Hoeffel's tactic was controversial.

Contact staff writer Emilie Lounsberry at 215-854-4828 or elounsberry@phillynews.com.

Inquirer staff writer Tom Infield contributed to this article.