WASHINGTON (CNN) -- Having just returned from a trip to Iraq, Sen. John McCain, R-Arizona, predicted the U.S. mission would succeed, but acknowledged Monday that it would be a "long and difficult" process.

"It is from my discussion with Gen. [David] Petraeus and the men and women who are serving there, some of them on their second, third and even fourth tours, that convinces me we are making some progress but that it will be long and difficult," McCain said at a news conference in his home state. "Unfortunately, the American people are not being told of the progress that is being made -- they should be."

McCain's comments come a day after the airing of a "60 Minutes" interview in which the GOP presidential candidate expressed regret for saying that Petraeus often travels around Baghdad in an unarmored humvee.

McCain is scheduled to deliver what the campaign is calling a "major policy speech" on Iraq Wednesday at the Virginia Military Institute.

The Arizona Republican also said popular radio talk-show host Don Imus should be forgiven for his controversial remarks about the Rutgers Women's basketball team.

"He has said that he's deeply sorry -- I'm a great believer in redemption, whether he needs to do more in order to satisfy the concerns of people like the members of that team, that's between him and them," McCain said.

-- CNN Ticker Producer Alexander Mooney