HARRISBURG -- State Rep. Michael Diven, a Brookline Democrat, is thinking about switching to the Republican Party to run for the now-vacant seat of former state Sen. Jack Wagner, say officials of both parties, both here and in Pittsburgh.

"I've been hearing that for some time now," Allegheny County Democratic Chairman Tom Flaherty said yesterday.

Diven said yesterday that he is using "due diligence to evaluate where I would be best positioned to serve my constituents in the South Hills and the city of Pittsburgh. ... I have to evaluate the role I want to play in Harrisburg and where I can be most effective for the residents of my district. I have not made a decision yet."

Several Republican political officials at the state Capitol also said yesterday that discussion was under way regarding Diven's candidacy.

Republicans already control the Senate 29 to 18, with three vacant seats. In November, one incumbent Democratic senator, Allen Kukovich of Westmoreland County, lost his seat to Republican Bob Regola. If Republicans were to take Democrat Wagner's seat it would be another blow to the already beleaguered Democrats.

Wagner's Senate district includes much of heavily Democratic Pittsburgh but also some western suburbs, where Republicans have been making inroads.

Diven, a former Pittsburgh City Council member, has been at odds with House Democratic leadership for some time, at some points even calling them "cowards" and "thugs."

Democratic House leaders angered Diven last spring by supporting a Democratic challenger, Rich Nerone, in the primary. It was an unsuccessful effort to oust Diven from his House seat.

Wagner resigned his Senate seat on Tuesday, when he was sworn in as the state's new auditor general. It is up to Lt. Gov. Catherine Baker Knoll, a political ally of Diven, to decide when to hold a special election to fill Wagner's seat. Knoll presides over the state Senate as one of her official duties.

Knoll has already set two other election dates to fill other Senate vacancies. A special election will be held April 5 to replace former Sen. Charlie Dent, R-Lehigh, who is now in Congress. Another election, to replace former Sen. Allyson Schwartz, D-Philadelphia, (who's also in Congress) will be held on the regular primary day of May 17.

Flaherty said holding a special election on a day other than the regular primary could aid an independent or Republican candidate, because it would be the only election that people would have to vote on that day.

The turnout would be generally smaller than on a regular primary day and an independent or a minority party candidate (such as a Republican) might have a better chance against the Democratic candidate.