HARRISBURG — The chairman of the State Board of Education said Wednesday he is leaving the board after being asked by Gov. Ed Rendell to give up his leadership post.

Karl Girton's resignation, effective Aug. 1, follows months of criticism of a board proposal that Pennsylvania students pass a series of tests before they can graduate high school. The 22-member board sets state education policy and regulations for K-12 public schools and higher education.

But Girton and a Rendell spokesman said the resignation was unrelated to controversy over the testing proposal, an initiative championed by Girton and the administration.

Girton, who has served on the board since 1992, said he spoke Friday by telephone with Rendell, who asked him to step down as chairman but stay on the board until the governor leaves office in 2011. After taking the weekend to think it over, Girton decided to leave the board altogether.

"There are no hard feelings," Girton said. "I just think it's in the best interest of the board that I decline his invitation to remain on the board. ... I don't think I would have been effective."

The governor felt the time was right to appoint a new chairman, given the recent turnover on the board, Rendell's spokesman Chuck Ardo said Wednesday.

"I don't think anybody is disappointed with his performance," Ardo said.

Seventeen of the board's members are nominated by the governor and confirmed by the state Senate. Eight new board members were confirmed to fill vacancies in April — the largest number of new members since Rendell took office, Ardo said.

Rendell waited to raise the issue of new board leadership with Girton because the administration was focused on completing the 2008-09 state budget and didn't have time to consider other issues, Ardo said.