He opposes abortion, including in cases of rape and incest. He thinks Iran could be deterred from aggression by deploying more warships. And he is a proponent of privatized Social Security.

But just one topic — his “9-9-9” tax plan — has dominated Herman Cain’s rhetoric in this presidential race, helping to propel him to the top of Republican polls this month.

And that has prompted questions about what else he stands for and whether he has the breadth of knowledge — particularly on foreign policy — expected of an occupant of the White House.

An examination of Cain’s words — his remarks as a radio talk-show host, as well as his writings, interviews and speeches — shows a man thoroughly steeped in conservative ideology. He has said that climate change is a scam, that he would not have survived cancer under the Obama administration’s health-care overhaul, and that the United States is on the brink of a socialist takeover.

In the style of an evangelist who can bring audiences to their feet, Cain has used his soapboxes to rebut criticism of the tea party movement, berate liberals and President Obama, and defend conservatives and Republicans against accusations of racism.

Reforming the tax code has been a keen interest since his days as the chief executive of Godfather’s Pizza in the 1990s. But outside of his tax ideas, Cain rarely gets into specifics. That is partly in keeping with his style of connecting with voters by communicating his ideas in basic, catchy terms.

“If you understand the simple concepts,” Cain writes in his recently published book, quoting an old teacher, “you will be able to deal with the complex concepts.”

It is also in keeping with his candor and the everyman persona he has cultivated on the campaign trail. Conservative audiences have found something compelling in his story, that of an African American who grew up in the segregated South and rose to become a successful business executive. And they have been energized by his passionate, humor-laced speeches.

In recent interviews, Cain has called it hubris to claim to know the minutiae of every major issue.

He has extolled the importance of leaders surrounding themselves with able advisers (though he has demurred when asked who his advisers are). He has shown repeatedly that, when faced with a tough question, he is not afraid to admit he doesn’t know the answer.

Asked during a campaign stop in New Hampshire this week about a specific deduction under his tax plan, he replied: “I have no idea. But it’s a good question.”

Cain offers a nine-page position paper he calls the “Cain Doctrine” in his book, “This is Herman Cain! My Journey to the White House,” which was published this month. In it, he proposes empowering states to resolve on their own challenges with illegal immigration, promoting greater domestic energy production and encouraging vigilance against the Islamic principles known as sharia law, which he warns could “seep into American life.”

He pledges support for Israel, but says he has too little information to opine on the war in Afghanistan or on events unfolding in other nations.

“It’s difficult to say how the Cain Doctrine would apply to the Middle East’s other countries, especially those affected by the ‘Arab Spring,’ and to nations elsewhere in the world,” he writes. “I’m not trying to escape the broader issues, but I think a president should first be briefed on classified intelligence about America’s relationships before offering opinions.”

Early in the campaign, Cain was criticized after he appeared unclear in an interview with Fox News’s Chris Wallace about the meaning of the Palestinian “right of return.” Cain has since studied the subject and visited Israel in August, a spokesman said.

More recently, he has proposed beefing up the nation’s ballistic missile capabilities and positioning warships in international waters as a show of force against Iran.

Cain also provoked controversy when he said repeatedly that he would not appoint a Muslim to his Cabinet. He later apologized and said he meant he would not appoint those with terrorist tendencies.

Cain is less conservative than some of his rivals on certain issues. He has said that he favors some forms of affirmative action, and he once opposed school vouchers, which he now supports. He also has not called for the wholesale elimination of the federal Education Department.

Cain, who is also a Baptist minister, has dabbled in social issues over the years. During an unsuccessful run for a U.S. Senate seat in Georgia in 2004, Cain made abortion the centerpiece of his campaign. He positioned himself to the right of the front-runner and eventual victor, Johnny Isakson (R), and argued that abortion should be permitted only when the life of the mother is threatened and not in cases of rape or incest.

But Cain’s interest in the tax code has been more of a signature issue, stemming from 1995, when congressional Republicans appointed him to a flat-tax commission.

Five years later, he became national co-chairman of the presidential campaign of Steve Forbes — before Cain, the best-known proponent of the flat income tax. Cain has since become a supporter of the “fair tax,” which would eliminate all federal taxes except a 23 percent national sales tax. He considers 9-9-9 to be a step toward that end.

Cain has also been a proponent of the “Chilean model” to reform Social Security. The South American nation established mandatory private retirement accounts for its citizens in 1981.

Still, his campaign has hinged almost exclusively on his proposal to throw out the tax code and replace it with a 9 percent income tax, a 9 percent business tax and a 9 percent national sales tax.

He uttered the series of digits 16 times over the course of a 90-minute debate this week hosted by The Washington Post and Bloomberg News. He brought it up recently when Fox News host Greta Van Susteren asked him his solution to the housing crisis. In a recent interview with The Post, Cain said he has become so closely associated with the plan that people often call out the numbers when they spot him at the airport.

“They think my last name is 9-9-9,” he joked. “That’s quite a compliment. That means it’s resonating. It’s easy to understand and powerful. I think that’s one of the reasons why people around the country are starting to know who I am and starting to identify me with solutions, not rhetoric.”

And Cain is unapologetic about the single-mindedness of his campaign. Asked recently whether he would be able to name the president of Uzbekistan, Cain mocked the name of the Central Asian nation and spoke derisively of “small insignificant states.”

“When they ask me who is the president of Ubeki-beki-beki-beki-stan-stan, I’m going to say, ‘You know, I don’t know. Do you know?’ And then I’m going to say, ‘How’s that going to create one job?’ ” Cain said in an interview last week with the Christian Broadcasting Network.

“When I get ready to go visit that country, I’ll know who it is,” he continued. “But until then I want to focus on the big issues that we need to solve.”

Staff writer Amy Gardner contributed to this report.

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