Republican gubernatorial nominee Jerry W. Kilgore said Tuesday that he has agreed to a debate that would include state Sen. H. Russell Potts Jr., but only if the independent candidate reaches 15 percent in two statewide polls between now and October.

Kilgore's campaign said the debate would be Oct. 9 in Richmond, though that date has not officially been agreed to by Lt. Gov. Timothy M. Kaine's campaign, which would like to hold the debate two weeks later.

The debate is the only one scheduled to be televised statewide. It was organized and would be moderated by Larry J. Sabato, director of the Center for Politics at the University of Virginia. Sabato said he did everything he could to ensure that a debate involving all three candidates on the ballot could be held under certain conditions.

"If I were the debate dictator, I'd have a three-way debate instantly," said Sabato, who based the 15 percent threshold for an independent candidate on the standard used by presidential debates for similar hopefuls. He added: "This was the best we could do."

The debate about debates -- how many to have and who should participate -- has been a contentious one in the gubernatorial campaign. Kaine, the Democratic candidate, has called for more debates. One debate has been held; another, sponsored by the Fairfax County Chamber of Commerce, is scheduled for Sept. 13.

Potts has relentlessly criticized Kilgore for refusing to debate him, and his campaign denounced the conditions for the new debate as unfair.

"It's a joke," said Tom D'Amore, Potts's campaign director. "It's a transparent run-and-hide strategy by Mr. Kilgore."

D'Amore said the fact that his candidate is on the ballot -- with more than 24,000 signatures from registered voters in Virginia -- should be enough to prove that he is a legitimate contender.

A recent survey of 625 likely voters by Mason-Dixon Polling & Research showed Potts receiving 9 percent of the vote; Kaine got 38 percent and Kilgore 37 percent. The poll also found that that 58 percent of respondents wanted to see Potts included in the debate.

Kilgore has maintained that he would not participate in a debate that includes Potts, a Republican state senator from Winchester, because he does not believe Potts has a chance of winning the election. Kaine has agreed to debate Potts, who is running as an independent, and the two have a confirmed appearance scheduled for Sept. 30.

Tim Murtaugh, press secretary for the Kilgore campaign, said that the decision to debate Potts under certain conditions was consistent with Kilgore's belief that such forums should be limited to those candidates who have made a significant showing among the state's likely voters.

"We have said all along that we would only debate candidates who have a chance of winning," Murtaugh said. "If the debate organizers set that bar at 15 percent, then we're willing to accept that."

Kaine's campaign said that Kilgore was responding to the will of the people in agreeing to the third debate. "It's clear that voters want to see a debate with all the candidates," said Mo Elleithee, Kaine's director of communications. "It's good to see Mr. Kilgore come around."

Potts could be a threat to both major-party candidates. The Mason Dixon poll found that much of his support comes from Republicans, though his positions on gay rights and abortion rights might attract some Democratic voters as he becomes better known.

"His campaign has hurt both of them, although Potts clearly has centered his criticisms on Kilgore," Sabato said. "But Kaine has to be worried about Potts's popularity in Northern Virginia and some of his stances that might be popular there."

The campaign of Lt. Gov. Timothy M. Kaine, left, says Jerry W. Kilgore, center, was responding to the will of the people in agreeing to a third debate. Kilgore has agreed to conditionally include Sen. H. Russell Potts Jr., right.