SALT LAKE CITY — The Utah Debate Commission announced Thursday that a debate has been scheduled Oct. 18 at BYU for candidates running to fill the 3rd Congressional District seat vacated by former Rep. Jason Chaffetz.

But just how many of the eight contenders on the November special election ballot will be allowed to take the stage will be determined by the results of polling already underway that are anticipated to be released mid-September.

The commission requires debate participants to meet a threshold of voter support in the poll of at least 10 percent, minus the margin of error, expected to be around plus or minus 4 percent.

Republican John Curtis, the mayor of Provo, and Democrat Kathie Allen, a Cottonwood Heights physician, could end up being joined in the debate by the new United Utah Party's Jim Bennett, UtahPolicy.com publisher LaVarr Webb said.

"I wouldn't be surprised if he gets 6 percent," said Webb, who writes a political column for the Deseret News. "If Bennett is there, I think it will be a more interesting debate."

He said he wasn't sure if any other candidates had a shot at meeting the threshold. UtahPolicy.com agreed to add the commission's question about support for the candidates to an already scheduled poll being conducted by Dan Jones & Associates.

United Utah Party Chairman Richard Davis said he thinks Bennett, the son of the late Sen. Bob Bennett, will be the first third-party candidate to participate in a commission debate.

"Jim is not a typical minor party candidate," Davis, a BYU political science professor, said, citing Bennett's longtime affiliation with the Republican Party and United Utah's high-profile court battle to be recognized by the state.

"That's clearly given him an edge," Davis said. "We're certainly keeping fingers crossed."

"We're always hopeful a third party will qualify," Nena Slighting, the commission's executive director, said, although only Republicans and Democrats have made the cut for previous commission debates.

The commission has had the same threshold for participation since it was launched in February 2014 and has been criticized in the past for not including third-party candidates.

“We have to be very clear with our process,” Slighting said. “Any time you are excluding candidates, you want them to know the reason why.”

This year’s special election attracted an unusually long list of candidates seeking to fill the remainder of Chaffetz's term after he unexpectedly announced he was stepping down. Chaffetz is now a Fox News contributor.

There are candidates from five political parties on the November ballot. Besides the Republican, Democratic and United Utah candidates, Libertarian Joe Buchman and Independent American Jason Christensen are running.

There are also two write-in candidates, Brendan Phillips and Russell Paul Roesler, and an unaffilated candidate, Sean Whalen.

Buchman said getting into the debate "would be a surprise but I have hopes."

He said as a Libertarian, he believes the commission had a right to set its own standards.

"The Utah Debate Commission is the Rolls Royce event. But if I’m not polling at 6 percent or so, I wouldn’t call that unfair," Buchman said, even though he has been invited to participate in other events.

Those events include a "Meet the Candidates" gathering in Provo in September organized by the Women's Legislative Council of Utah County alongside Allen, Curtis and Whalen.

The commission debate is scheduled for 6 to 7 p.m. on Oct. 18 at the BYU studios on campus and will be moderated by BYU political science professor David Magleby.

Also Thursday, final election results from the three-way Aug. 15 Republican Party primary race in the 3rd Congressional District were certified by Lt. Gov. Spencer Cox.

Curtis won with 43 percent of the vote over former state lawmaker Chris Herrod, who was in second place with 33 percent, and Alpine lawyer Tanner Ainge, who came in third with 24 percent, according to the results.

Herrod, the winner of the 3rd District GOP delegate vote, waited several days to concede while outstanding votes in the largely by-mail election were counted, even though The Associated Press declared Curtis the winner on election night.

Turnout was 40 percent among Republicans in the 3rd District, which includes portions of Salt Lake and Utah counties as well as Carbon, Emery, Grand, San Juan and Wasatch counties.

Contributing: The Associated Press