PITTSBURGH — Allegheny County Executive Dan Onorato will kick off his campaign for the Democratic nomination for governor on Tuesday.

The 48-year-old is in his second term as county executive and was formerly a Pittsburgh councilman and county controller. He'll stop in Philadelphia, Harrisburg and Pittsburgh to kick off his campaign.

Onorato will compete with Philadelphia businessman Tom Knox, Scranton Mayor Chris Doherty and Montgomery County Commissioner Joel Hoeffel for the 2010 nomination.

Attorney General Tom Corbett will face state Rep. Jim Gerlach of Chester County for the Republican nomination.

HARRISBURG — Republicans retained their 10-seat majority in the state Senate after GOP Rep. Bob Mensch handily won a special election to fill a vacant seat.Returns from all 123 precincts in the southeastern Pennsylvania district showed Mensch won 12,496 votes, or 66 percent. The Democratic candidate, Lansdale councilwoman Anne Scheuring, had 5,730 votes, or 30 percentThe 24th Senate District includes parts of Montgomery, Lehigh, Bucks and Northampton counties.Mensch's victory keeps the Senate lineup at 30 Republicans and 20 Democrats.