It's never a good idea to change horses in the middle of a stream, and this is particularly true when astride a thoroughbred in treacherous waters.

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PG AUDIO

Incumbent Republican Tom Corbett and Democratic challenger John Morganelli talk about their campaigns for state Attorney General.

• Tom Corbett
• John Morganelli

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State Attorney General Tom Corbett faces voters in his quest for a second full term while in the midst of a high-profile investigation of the Pennsylvania Legislature, a circumstance that could prove to be an asset or a drawback. The work of his grand jury, which already has resulted in criminal charges against a dozen Democrats, has been both praised and vilified.

It is not surprising that his loudest critic has been John Morganelli, the Northampton County district attorney who is the Democratic nominee. Also on the ballot but outmatched in experience for this position is Libertarian Marakay J. Rogers, 46, a York attorney who, as the Green Party nominee, ran for the office in 2004 and withdrew from the race for governor in 2006.

Mr. Morganelli raises some interesting questions about the probe, but his contention that Mr. Corbett, a Republican, has botched the Bonusgate investigation is overblown.

Mr. Morganelli says an independent prosecutor should have been put in charge and that all four caucuses -- Democratic and Republican, House and Senate -- should have been investigated simultaneously. Because that didn't happen, Mr. Morganelli believes the investigation is tainted by politics and that its eventual outcome has been jeopardized. A television commercial that he began airing last week includes the bold misstatement that Mr. Corbett took money from individuals whom he subsequently "refused to prosecute."

In conducting the investigation of the Legislature, Mr. Corbett followed the No. 1 rule of public corruption inquiries: Follow the money. In 2006, the House Democratic caucus awarded employee bonuses worth $1.9 million, a sum that far eclipsed extra pay handed out by Senate Democrats and Republicans in both chambers. In addition, the case against House Democrats had to advance quickly once investigators learned documents were being destroyed. It was Mr. Corbett's duty to act on that information, rather than wait while evidence from other parts of the Legislature was being compiled.

We have been unhappy with Mr. Corbett's position that no new presentments would be issued in the month leading up to the election, a practice he adapted from the U.S. attorney's office, but he says that now is a moot point because no charges are ready. In an unusual turn, he also said the grand jury will release a full report even if no further allegations develop.

Mr. Corbett, 59, of Shaler started his legal career as an assistant district attorney in Allegheny County and then moved to the U.S. attorney's office as an assistant in 1980. Nine years later, the first President Bush appointed him as U.S. attorney for the Western District, a post he held until 1993. In 1995, Gov. Tom Ridge appointed Mr. Corbett as state attorney general when Ernie Preate, the first person to hold the job, was sent to prison.

Mr. Morganelli, 52, of Bethlehem also brings a strong resume to the campaign. A graduate of Villanova School of Law, he was elected district attorney in 1991 and he has been re-elected without opposition four times. He has personally handled first-degree murder trials; held leadership positions, including president, of the Pennsylvania District Attorneys Association; and teaches law part-time at Moravian College, his alma mater.

In addition to being dissatisfied with the performance of the attorney general, Mr. Morganelli also is unhappy with how the office is constituted. He describes Mr. Corbett's style "as a super district attorney" and says, rather than adopt that approach, he would emphasize the consumer protection and anti-trust aspects of the civil side of the office. He would lobby to abolish credit scoring for consumers, contending that it discriminates against poor people, and would use the office to oppose unsafe products entering U.S. markets. In addition, he favors a constitutional change in duties, arguing that each state department and bureau already has its own team of lawyers and does not need the independent outside counsel that the AG's office provides.

Mr. Morganelli claims Mr. Corbett has been quiet for four years except for Bonusgate, but he is wrong. We think Mr. Corbett is needed to finish the Bonusgate investigation he began, but that is not the sum of his accomplishments during the past four years.

In addition to the public corruption unit, Mr. Corbett created a child predator section that has arrested more than 160 child sex-abusers and his staff presents effective and age-appropriate educational programs for adults and children on Internet dangers. He has continued multijurisdictional drug prosecutions, long a staple of the office, and he created a unit that coordinates efforts to fight fraud aimed at older Pennsylvanians.

His Web site is a useful spot to register for Pennsylvania's Do Not Call list, to lodge complaints against unscrupulous businesses and to get advice to guard against identity theft and on many other practical topics.

The Post-Gazette endorses Tom Corbett for another four years as Pennsylvania's chief law enforcement officer.