HARRISBURG — Less than a month after a state Supreme Court justice was convicted of campaign corruption, three former Pennsylvania governors renewed a call Monday to remove appellate court judges from the electoral process and instead seat them through a process more like that used to pick federal judges.

The calls from Democrat Ed Rendell and Republicans Tom Ridge and Richard Thornburgh for a “merit selection” process come after state Supreme Court Justice Joan Orie Melvin was convicted of using her Superior Court staff for a pair of campaigns for a spot on the Supreme Court.

Such a change would require state lawmakers to allow a referendum, but the Legislature has shown little inclination to change a system that some of them say already allows voters to have the ultimate decision.

“There’s a lot of people who consider that we already have merit selection, via the election process,” said Steve Miskin, a spokesman for leaders of the state House Republican majority.

The former governors made the same plea in 2010, without success, to detach judges and justices from a fundraising and campaigning process that, they say, creates a public perception of bias.

“That whole process casts, I think, a very dark shadow, a heavy cloud over the integrity and the independence of our judicial system,” Ridge told reporters on a conference call arranged by the Philadelphia-based group, Pennsylvanians for Modern Courts.

Said Rendell, “It creates a feeling among ordinary folks that the system is for sale.”

Thornburgh said he has worked on the issue for nearly 50 years going back to Pennsylvania’s last constitutional conference of 1967-68, when it was defeated in a referendum.

Changing the current system would require a constitutional amendment. To do so, the state House and Senate must each approve the proposed amendment in each of two consecutive two-year sessions before voters must approve it in a statewide referendum.

Pennsylvanians for Modern Courts envisions a commission of lawyers and regular citizens appointed by the governor and legislative leaders screening applicants for judicial vacancies and recommending the most qualified to the governor, who then picks one to nominate for Senate confirmation.