HARRISBURG -- It's unusual for a political candidate who is far ahead in the polls, and almost certainly in campaign cash, to wage an aggressive attack on the challenger who's badly trailing.

But that looks like what Attorney General Tom Corbett is planning against state Rep. Sam Rohrer of Berks County, his only challenger in the May primary for the Republican nomination for governor.

Mr. Corbett has filed a Right-To-Know request with the state House clerk's office seeking all of its records on Mr. Rohrer's voting record, expenditures and expenses for travel, lodging and other things, during his years in the House, which began in 1993.

"We are looking into his record as a public official," said Corbett campaign Manager Brian Nutt. "In a primary, you try to find out as much as you can about your opponent's record."

One of Mr. Rohrer's main strengths in the primary will almost certainly come from rightward-leaning Republicans, because he is in the conservative wing of the party. Loud protests over "big government" and "high taxes," led by members of the so-called "Tea Party" movement, have also become a political fact of life, especially for Republicans.

The surprise victory last week in Massachusetts for Republican Sen. Scott Brown also showed the properly harnessed clout of conservative independent and Republican voters.

Mr. Corbett, of Shaler, generally is seen as more middle-of-the-road than Mr. Rohrer, although Mr. Nutt said Mr. Corbett will make a strong pitch for conservative votes also. One Corbett strategy will be to cast doubt on whether some of Mr. Rohrer's past votes were really of a "conservative" nature.

For example, Mr. Nutt said that Mr. Rohrer voted in 2001 for a significant increase in pensions for retired state workers, a move that Gov. Ed Rendell now says could cost the state at least an additional $2 billion starting in 2012. State officials haven't figured out how to pay for the hefty pension increase.

Mr. Rohrer also voted for the controversial 16 to 34 percent legislative pay raise in July 2005, which later was repealed in the face of loud public opposition.

"Sam says he's a conservative, but a lot of people have told us to look at his record," Mr. Nutt said. "Pay raises and pension increases aren't exactly fiscally conservative moves."

Digging up information on Mr. Rohrer is a change of focus for the Corbett camp.

Several months ago, Mr. Rohrer wasn't even in the race, while Mr. Corbett faced challenges from Jim Gerlach, a GOP Congressman from suburban Philadelphia, and Pat Meehan, a former U.S. attorney in Philadelphia. But they both decided to run for Congress this year instead of governor. Polls showed Mr. Corbett considerably ahead of both of them, but they haven't really measured him in a one-on-one race against Mr. Rohrer.

The exact numbers for campaign funds won't be known until the candidates' reports are released Feb. 1. But Mr. Corbett, who has gotten the public support of many top GOP officials, is expected to have a healthy fundraising edge.

Another aspect of Mr. Rohrer's legislative career that may be examined is his longtime push for eliminating property taxes, which hasn't gone anywhere. One reason is that it would require sharp increases in state income taxes and/or sales taxes to make up for the $7 billion or more that would be lost by ending property taxes, and legislators are reluctant to vote for them.

Mr. Rohrer, who isn't seeking re-election to the House this year, maintained that talking about his vote for the pay raise is merely a way to avoid discussing real issues. The Corbett campaign, he said last week, is "trying to stay as far away from the issues as they can."

Asked if he thinks the pay raise vote will be a way for Mr. Corbett to damage him, Mr. Rohrer insisted, "It won't be."

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