LANCASTER, Pa. -- In this famously Republican place, Tom Corbett, the frontrunner for the party's gubernatorial nomination, gave a speech on an all-but-empty porch while Sam Rohrer, his single-digit opponent, packed two halls.

To date, no one has predicted a Rohrer breakthrough. Still, his insurgent candidacy has captivated pro-lifers, tea partiers and states-rights advocates in a way that made a pro forma primary a test of what conservative principles the state's generally moderate GOP will embrace and how hard it will hug.

"Right now you have a phenomenon with the voters, whether they be independent, Republican or Democrat, are upset with Harrisburg and upset with Washington to the point that they're not sure who they're upset with," Mr. Corbett said.

Mostly, they seem to be staying away.

"People aren't engaged yet," Mr. Corbett said.

On a visit to the Hershey Farm Restaurant and Inn, a tourist destination usually swimming in people, Mr. Corbett toured the grounds, inspected its privately owned sewage treatment plant, talked tourism with the manager, then prepared to address what turned out to be a non-crowd.

With almost nobody handy at midday, manager Deryl Stoltzfus scrambled to round up a half-dozen staff to hear Mr. Corbett give his ideas for job growth and business expansion.

The speech was pure manager: on point and hitting the "mission statement" refrains of his party. He wants to rein in the budget, lower taxes and reduce regulations on business, convinced that the economy can flourish if its businesses are unfettered.

Two hours later and six miles away, Mr. Rohrer's advance team planted signs, worked the telephones and e-mail addresses and delivered 45 people to a small room at a local business park. To get there they had to maneuver traffic on Route 30, find a gate by the back lot then pass through an iron-fenced plant guard booth to hear their man.

Mr. Corbett is the endorsed candidate of his party's leadership and well enough funded for a hefty television advertising budget. Statewide polls have consistently given him a wide lead, with 58 percent of voters polled favoring him. Mr. Rohrer himself concedes his own internal polls show him lagging, though he has continued to build a network among disaffected conservatives already distrustful of their party and religious evangelicals.

"This is eye-to-eye and it's powerful," Mr. Rohrer said as an assemblage of older Lancaster residents filtered into a room off the cafeteria of Burle Industrial Park, took seats at a table and waited for him to speak. A nine-term state House member from Berks County, Mr. Rohrer is forgoing another run for the Legislature to challenge Mr. Corbett.

"Sam has Reagan values," declared Rick Armellino, a manufacturing company head who introduced the candidate. In fact, Mr. Armellino added, Mr. Rohrer might be more promising because Reagan "got snookered a couple of times."

Mr. Rohrer's speeches are long, sometimes painfully detailed, and almost evangelical in their fervor for the same conservative principles Mr. Corbett holds but professes with cool detachment.

His voice thin, Mr. Rohrer speaks more loudly with his hands. He points, pokes, gesticulates, waves his arms, sometimes sweeps the space in front of him as if he were gathering up words just spoken for a reload.

"We home-school our children, so you know what we've chosen to do educationally," Mr. Rohrer told the crowd. Warm applause followed.

Lancaster is among the most socially conservative counties in a state known for centrist Republicans. As such, Mr. Rohrer views it as a key to any hopes of breaking through Mr. Corbett's seeming hammerlock on the nomination.

It is the kind of place where a man like Sam Menefee, a retired pilot, on his first meeting with the candidate, opened the conversation with this question:

"What is your concept of God and how do you relate that concept to how it would guide you as you govern?"

Mr. Rohrer called it "a great question" and expounded in detail on his ideas of a universal, moral order and its religious core. Mr. Rohrer is an independent Baptist and received a degree in business management in 1977 from Bob Jones University, the fundamentalist religious school in Greenville, S.C.

Mr. Corbett, a lifelong Catholic, holds the same views on morality. In fact, the men are barely any distance from each other on abortion, gun control, even states rights. Mr. Corbett is among Republican attorneys general challenging the constitutionality of the federal health care reform bill, and both he and Mr. Rohrer have called Pennsylvania's acceptance of federal economic stimulus money a mistake.

Yet where Mr. Corbett speaks in terms of management, Mr. Rohrer, with his references to home schooling and declarations on ethics and morality, appeals to conservatives distrustful of their own party and digging for a vein of unmistakable authenticity.

"He's talking in five or six points broadly," said Mr. Corbett. "I've never been bombastic. That's just not me."

Mr. Corbett's Republican credentials are long-standing. He was born in Philadelphia, the son of a Republican lawyer who moved the family to Pittsburgh two years later to work on the acquisition of land for what later became Point State Park as well as Allegheny Center. The elder Corbett later became a deputy attorney general under Gov. Ray Shafer. In those years, the state's attorney general handled only civil litigation. The job would not become a prosecutor's post until state law was changed in the late 1970s.

The younger Corbett attended Lebanon Valley College in the state's center, then law school at St. Mary's University in San Antonio, Texas. He returned to Pittsburgh and took a job as a deputy district attorney under Robert Colville before moving to the U.S. attorney's office in Pittsburgh.

As a two-term attorney general in Pennsylvania, Mr. Corbett gained name recognition and some criticism for an aggressive series of grand jury investigations into the legislative spending scandal that came to be known as Bonusgate. His first round of grand jury presentments snared a collection of former state legislators, including former House Minority Whip Michael Veon, D-Beaver. Amid criticism that he was targeting only Democrats, he later unloaded scores of criminal counts against the Republican former state House Speaker, state Rep. John Perzel, R-Philadelphia.

He has made it clear he'll run on that record, but to date, the primary challenge from Mr. Rohrer has pushed Mr. Corbett to shore up his conservative credentials, leaving little time for internal party messages about crime-busting.

"You might see that coming," Mr. Corbett said, "but right now we don't need that for the primary."

While maximizing his support on his party's hard right, Mr. Rohrer almost always finds himself confronting the unpleasant question about his 2005 vote in favor of a legislative pay raise, as well as his vote to increase legislative pensions. Consistently, he describes it as "the one vote I wish I hadn't made." He spins it as a case of having given his word to party leaders in advance, then holding his nose while keeping his word.

Generally, this doesn't turn off his core supporters. Mr. Corbett rarely bypasses a chance to point out the Rohrer vote.

"He says he's the conservative, but he's the one that voted for the pay raise and voted for the pension increase," Mr. Corbett said. "I allow my actions to speak for me. Sam is speaking for his actions. Or just speaking."

Looking for more from the Post-Gazette? Join PG+, our members-only web site. You'll get exclusive sports content, opinion, financial information, discounts from retailers and restaurants, and more. Our introduction to PG+ gives you all the details.