Proponents of so-called merit selection of state appellate judges are hoping those big names can help gather popular support for the long and grueling road toward a constitutional amendment.
Most states, including New Jersey, have some form of a merit selection system.
Under the system, the governor would be able to appoint judges, but could select them only from a pool of applicants screened and preapproved by a bipartisan nominating commission.
The former Pennsylvania governors' proposal would have governors appoint judges to the state's three appellate benches - Commonwealth, Superior and Supreme Courts. Municipal and Common Pleas Court judges would still have to campaign to win their seats in partisan races. Merit-selection supporters reason that voters are more familiar with local candidates.
"When it comes to statewide judges, very few voters know who they are, and if they do know who they are, it's for the wrong reasons," Thornburgh, now working for the law firm K&L Gates, said Friday.
Supporters of judicial elections have long argued that letting governors choose judges would be simply a return to backroom politics that takes decision-making away from ordinary citizens.
But successive Pennsylvania governors have floated the idea nonetheless, with Rendell urging legislators to pass merit selection as recently as 2010 and Ridge hosting summit meetings on the topic before he left office in 2001.
Thornburgh has championed the change for years, beginning with an effort at the 1967 state constitutional convention to pass merit selection. But in a referendum, voters decided to keep judicial elections instead.
"Amending the constitution to change the way Pennsylvania selects appellate court judges is a decision that should not be undertaken lightly," the ex-governors wrote in their letter, made public Friday. "Like all constitutional amendments, it is a topic worthy of extensive discussion and debate. We simply ask that you act to begin that process."
Whether their endorsement will make any difference in Harrisburg remains to be seen. But Lynn Marks, who runs Pennsylvanians for Modern Courts, a pro-merit-selection organization, said their coming together is significant.
"It's highly unusual," she said Friday. "It points to the seriousness of this. And I think it's important it's bipartisan."
Marks said shutting down a statewide election process sounds counterintuitive to many voters. But, she argued, members of the judicial branch should not be engaging in partisan politics.
For the legislative and executive branches of government, "people run on a party line, they run on a platform. It makes sense for them to raise a lot of money," she said. "Judges, on the other hand, are supposed to make decisions in individual cases based solely on the facts and the law."
Members of the legislature have expressed some support for merit selection in the past, with lawmakers typically introducing bills to end judicial elections during each session, said Bill Patton, spokesman for the state House Democratic Caucus.
Gov. Corbett supports merit selection for appellate judges, a spokeswoman said Friday.
The issue has gained renewed attention in recent months thanks to headlines about high-profile cases of judicial misconduct. The seven-seat Supreme Court has just six justices hearing cases after suspended Justice Joan Orie Melvin was convicted in February on six criminal charges. Jurors found that she had illegally used state-funded staff on her campaigns.
State House members recently submitted a merit-selection bill, Patton said, but lawmakers have typically shied away from the idea because "they need to know more clearly what the exact mechanism would be."
As the ex-governors noted, making such a change is no mean feat. It requires amending the state constitution, a process that stretches across two two-year legislative sessions, plus a statewide referendum.
One Philadelphia defense lawyer cautioned against seeing an appointive system as a cure-all for corrupt campaigns or sleazy judges.
"It's still going to be a political process. It will just move to a different venue," former prosecutor George Parry said Friday. "But I would expect that [a merit selection committee] would have some level of potential embarrassment if they picked a complete idiot for the bench."
In the existing system, Parry said, "a complete idiot can run for judge, and depending on ... how much money he or she has to devote to the cause, he or she can get elected."
Contact Aubrey Whelan at 610-313-8112, firstname.lastname@example.org or on Twitter @aubreyjwhelan.