CBS host Bob Schieffer scolded Republican presidential candidate Herman Cain Sunday for an online ad that prominently features his top advisor smoking a cigarette.

Cain explained that while he doesn't personally smoke, he didn't have a problem with Mark Block's smoking hadbit: "I don't have a problem if that's his choice."

"It sends a signal that it is cool to smoke," Schieffer noted.

"No, it does not," Cain argued. "Mark Block smokes. That's all that ad says. We weren't trying to say it's cool to smoke. We have a lot of people in this country that smoke, but what I respect about Mark as a smoker, who is my chief of staff, he never smokes around me or smokes around anyone else. He goes outside."

"He smokes on television," Schieffer pointed out.

"If they listen to the message where he said America has never seen a candidate like Herman Cain. That was the main point of it. The bit on the end we didn't know whether it would be funny to some people or whether they were going to ignore it or whatever the case may be," Cain said.

"It's not funny to me. I am a cancer survivor like you," Schieffer remarked. "I had cancer that was smoking related. I don't think it serves the country well -- and this is an editorial opinion here -- to be showing someone smoking a cigarette. You're the frontrunner now. It seems to me as frontrunner you would have a responsibility not to take that kind of a tone in this campaign. I would suggest that perhaps as the frontrunner, you'd want to raise the level of the campaign. ... Would you take the ad down?"

"It's impossible to do now," Cain claimed. "Once you put it on the Internet, it goes viral. We could take it off of our website, but there are other sites that have already picked it up. It's nearly impossible to erase that ad from the Internet."

"Have you ever thought of just saying to young people, 'Don't smoke'?" Schieffer asked. "Four hundred thousand people in America die every year from smoking-related [diseases]."

"I will have no problem saying that," Cain insisted.

"Say it right now," Schieffer demanded.

"Young people of America, all people, do not smoke," Cain said. "It is hazardous and it's dangerous to your health. Don't smoke. I've never smoked and I have encouraged people not to smoke. ... It is not a cool thing to do. That's not what I was trying to say. Smoking is is not a cool thing to do."

Watch this video from CBS's Face the Nation, broadcast Oct. 30, 2011.

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