The front-runners - Democrat Don Onorato and Republican Tom Corbett - were both planning to visit polling places in the Pittsburgh area as voters cast ballots in Tuesday's primary.
A Quinnipiac University poll released Monday showed Onorato - Allegheny County's elected chief executive - with 39 percent of the vote in the four-way Democratic race.
The other candidates had less than 15 percent each - state Sen. Anthony Hardy Williams of Philadelphia, state Auditor General Jack Wagner of Pittsburgh and Montgomery County Commissioner Joe Hoeffel.
Corbett, the state attorney general, had a 4-1 polling edge over his only foe, state Rep. Sam Rohrer of Berks County.
Rendell, a Democrat, is barred by law from seeking a third term.
