ATLANTA (AP) — The Republican front-runner in the Georgia governor's race said in a secretly recorded conversation that he pushed and helped pass an education measure he considered "bad public policy" in order to deprive a political rival of campaign support.

In the recording obtained by the Atlanta Journal-Constitution and WSB-TV , Republican Lt. Gov. Casey Cagle says his decision to support raising tax credits for private school scholarships "ain't about public policy. It's about (expletive) politics."

Clay Tippins, who finished fourth in the GOP gubernatorial primary, said he spoke with Cagle two days after the May 22 primary and covertly recorded the conversation on his cellphone out of frustration with Cagle.

Cagle is locked in a contentious runoff for the GOP nomination with Secretary of State Brian Kemp that will be decided July 24.

The bill in question, which was signed into law by Gov. Nathan Deal on May 7, raised the cap on tax credits for private school scholarships from $58 million to $100 million.

Cagle said in the recording that he was "playing defense" and needed the bill passed in hopes of stopping a group that has backed charter school initiatives nationwide from spending a large sum to support the campaign of former state Sen. Hunter Hill. An outspoken supporter of school-choice policies, Hill came in third in the GOP race for governor, ahead of Tippins.

In a statement Friday, Cagle defended the measure while saying it wasn't perfect. He said he answered Tippins' questions "open and honestly" and pledged to advocate for any legislation that expands education options.

"The bill wasn't perfect — and I said that to Clay — but we reached a broad agreement while no side got everything it wanted," Cagle's statement said.

Cagle's description of the tax credit increase in the conversation recorded by Tippins goes farther than merely describing it as imperfect.

"They wanted that $100 million SSO," Cagle says on the recording, using the abbreviation for the tax credit program's name, Student Scholarship Organizations. "And, you know, I was the only guy standing in the way. Is it bad public policy? Between you and me, it is. I can tell you how it is a thousand different ways."

The program, which has been criticized for diverting money from public schools, allows organizations to provide scholarships for children to attend private schools and then receive a tax credit for the amount they donate.

The bill was staunchly opposed by state Sen. Lindsey Tippins, Clay Tippins' uncle, who then chaired the Senate Education Committee, but was pushed through with Cagle's backing over Sen. Tippins' objection.

Clay Tippins, who has not yet made an endorsement in the race, told the Atlanta newspaper that he recorded the private conversation because he was "furious" and wanted to give voters a "window into Casey Cagle's character."

The recording seems likely to offer a new refrain for Kemp's campaign, which has focused on attacking Cagle as a political insider and career politician. Kemp said the recording "raises serious ethical and legal questions that must be answered immediately."