The only openly gay Republican exploring a presidential bid is fighting to be included in an upcoming candidates forum hosted by the Iowa Christian Alliance.

Fred Karger, a retired GOP consultant from California, told The Ballot Box he's been excluded from the March 7 event because of his sexual orientation.

But Steve Scheffler, president of the Iowa group, said Karger wasn't among the 15 potential candidates invited to attend because he only talks about one issue — gay rights. "We're inviting all potential candidates who are legitimate candidates," Scheffler told The Ballot Box. Karger "is not a legitimate candidate."

"That’s code for homophobia," said Karger, who worked as a consultant on the late Ronald Reagan's campaigns for governor and president. "I'm going to send him a letter and ask that I be included, and I'm going to look to the [Federal Election Commission] to see what the rules are."

After a career in campaign politics during which he kept his orientation hidden, Karger retired into the role of gay-rights advocate. He's considering a run for president, he said, in order "to send a message to younger people." And he's already begun laying the groundwork for a campaign.

Karger has formed an exploratory committee, but is using his own money to fund his travel to Iowa and New Hampshire, where he has two staff members.

“I’m going to fight, as many potential candidates do, to get into these forums and debates, and I will. This is number one," he said.

Karger said Scheffler has tried to menace him out of entering the race for the Republican nomination.

"[He] threatened me in a personal e-mail,” Karger said. "[Scheffler said] he'd work overtime to abort my candidacy."

Scheffler declined to comment on his exchanges with Karger.

The forum is expected to draw potential GOP presidential contenders such as Mitt Romney, Tim Pawlenty and Sarah Palin. The Iowa Christian Alliance also invited former New Mexico Gov. Gary Johnson (R), who is a staunch advocate for legalizing marijuana.