Attorney General Tom Corbett needs to develop a thicker hide if he wants to be governor.

Corbett, the GOP nominee, used a grand jury subpoena in an attempt to learn the identities of two anonymous bloggers who have been among his harshest critics on the Internet. This stunt smacks of an abuse of a prosecutor's powers for political gain.

The subpoena sought information from Twitter Inc., based in San Francisco, for the identities of a blogger who posts commentary about Corbett on a blog named "CasablancaPA," and another blogger called "bfbarbie." They've criticized Corbett relentlessly for his handling of the so-called "Bonusgate" probe, a wide-ranging corruption prosecution involving multiple defendants in the state legislature.

Corbett and his staff believe one of the pesky anonymous critics is defendant Brett Cott, a former top Democratic House aide convicted of conspiracy for diverting public money to wage political campaigns. A judge sentenced Cott on Friday to 21 months to 5 years in prison, and ordered him to pay $61,000 in fines and restitution.

Before Cott was sentenced, however, the Attorney General's Office attempted to prove Cott was the author of some of those blog posts. Corbett's office said this fishing expedition was necessary because it would show that Cott lacked remorse and that he merited a stiffer sentence.

It's becoming increasingly difficult to separate Corbett the crusading prosecutor from Corbett the candidate for governor.

Two months ago, Corbett filed suit with other states' attorneys general to block implementation of the federal health-insurance law in Pennsylvania. He contends the bill is unconstitutional, but the move could only have improved his standing among conservative voters in the GOP primary.

A spokesman for Corbett said the subpoena for Twitter was not intended to stifle speech, noting that other bloggers have criticized the attorney general without repercussions. But it's obvious that "CasablancaPA" and "bfbarbie" have been irritating Corbett for some time.

"We know people like Brett Cott are on the blogs all day, making stuff up," Corbett told the Associated Press last year.

Whether they're making up stuff or not, even people facing criminal charges have a right to air their views, about everything from perceived injustice to the quality of last night's cheesesteak. Using the machinery of the criminal-justice system to unmask blogging shows that the attorney general has a thin skin and, worse, poor judgment.

After the judge gave Cott a longer sentence than Corbett had requested, the Attorney General's Office said it will no longer pursue the subpoena because the issue is "moot."

But the episode is still highly relevant for voters, who should consider how a Gov. Corbett would tolerate criticism, and whether he knows when to back off the levers of power.