CONCORD, N.H. -- Herman Cain will not endorse a candidate in the Republican presidential primary, saying that such a move might imperil his larger goal: promoting his 9-9-9 tax plan.

In a phone interview Wednesday with The Atlanta Journal-Constitution, the morning after the New Hampshire primary, Cain said it was “bittersweet” to be no longer competing for the presidency. The campaign of the McDonough businessman was derailed in part by allegations of sexual misconduct that Cain maintains were false, yet still fatal to his bid.

He intends to mount a nationwide bus tour to promote his “Cain solutions,” most prominently his plan for a flat 9 percent tax on personal income, corporations and sales that became his campaign trail mantra. There is no itinerary yet for the tour, but Cain said he has been flooded with speaking requests.

Cain will speak Jan. 19 at the Southern Republican Leadership Conference in Charleston, S.C., two days before the South Carolina primary. He said he will use that speech to make an “unconventional endorsement” in the presidential race, which means that he will not be blessing a single candidate.

“My mission is to help defeat Barack Obama,” he said. “I want my supporters to stay excited and enthused. And if I pick one person, some of them may not like that one person, and that would fragment my supporters.”

Cain said he does not plan to seek the presidency or any other political office in the future.

“I never say never,” he said, “but based on what I know today, I probably will not run again, because my biological clock is ticking.”

Cain, 66, said he figures he has nine -- yes, nine -- good years left, and he does not want to spend them campaigning for office. In addition to the bus tour, Cain will offer commentary on radio and television. He will be a regular guest on Neal Boortz's radio show on Mondays and Fridays. Cain said he also will appear regularly on Sean Hannity's national radio and television shows -- though the details have not been finalized. Cain also will remain a contributor on Fox News.

Once his new venture is fully staffed, Cain said he will have about 25 to 30 people working to promote his ideas. His chief adviser remains Mark Block, his presidential campaign’s chief of staff. For tax purposes, there are four separate entities Cain operates: a Super PAC, a 501(c)3 charitable organization, a 501(c)4 social welfare organization and an S corporation, the New Voice Inc.

Their immediate goal is to push 9-9-9. Cain said his staff is working on drafting a bill to implement the tax plan -- which he insists will incite explosive growth but was questioned by many economists during the campaign and has not been adopted by any of the other candidates. The next step, Cain said, is to put pressure on members of Congress to co-sponsor the bill and build a grass-roots support “so compelling that it will be almost impossible for a Republican Congress to be able to stop it.”

When asked why anyone would pay attention to his ideas anymore as he is no longer running, Cain replied, “If you go to my website, cainconnections.com, we have almost 400,000 people that have already signed up. Is that a good indication that they still want me to do this?”

At one point, Cain was leading in national polls in the GOP presidential primary, but his campaign began to unravel after news reports revealed that a couple of women had accused him of sexual harassment while he was head of the National Restaurant Association in the 1990s. Then Ginger White of Dunwoody came forward and said she had a long-running affair with Cain.

Cain denied all of the allegations, but the continued scrutiny put an undue strain on his family, he said. His standing in the polls began to drop as a result of the allegations as well as Cain’s gaffes when discussing foreign policy and other matters. He announced that he was ending his campaign at a Dec. 3 rally in Atlanta.

“When you run for office, you can’t anticipate everything -- especially those things that are unexpected,” Cain said, defending his campaign strategy. “How do you anticipate somebody fabricating -- fabricating -- stories in order to create a solid doubt in the minds of some of the voters?”

Cain said he believes “somebody was behind those attacks,” but he does not have evidence to back it up.

He said he is displeased with the increasingly negative tone of the presidential race and proud that he kept things positive.

“I don’t regret it at all,” Cain said. “I just regret the way it ended.”