TYLER, Texas — As goofs go, John McCain's slip at a town hall forum Friday was a small one. Contrasting himself with his likely Democratic opponent, he said, "I'm a proud, conservative, liberal Repub — " Then he caught himself, just as the audience started laughing.

"Hello! Easy there. Let me say this," he tried again. "I am a proud, conservative Republican."

The slip of the tongue prompted Internet headlines all day, given the trouble the presumptive Republican nominee has had in convincing conservatives that he is not a liberal. But the moment summed up how McCain plans to campaign: by using charm, bluntness and humor in one town hall after another all across America.

The Republican senator from Arizona, who is expected to mathematically clinch the nomination with party vote victories Tuesday in Texas and Ohio, took the weekend off before campaigning tomorrow in Lubbock and Waco.

From the back of a 1980s-era bus, he will travel to college campuses, company break rooms and town squares. Between stops, he will hold court with small groups of reporters on the bus' faux-leather couch. And once a day or so he will hold a rally.

Then he will get on a plane and take the show to another state. It's a quaint and inefficient way to sell a candidate to the American people, especially if McCain will be facing Barack Obama, whose rock-star persona can fill a stadium with 20,000 screaming fans.

But McCain and his top advisers believe he has no choice: It's simply who he is.

"We'll try to just do the same thing we have been doing, only with a wider audience," McCain told reporters on his Straight Talk Express bus in Ohio last week. "I admit that it's difficult. But I think we can do it. You've got to maintain the same flavor of the campaign that we have throughout."

On Wednesday, McCain fielded questions from a few of the 400 voters who showed up in Tyler and then he hopped a short flight to San Antonio for a town hall event at a large insurance company that caters to the military and veterans. On Thursday, he answered questions from students at Rice University in Houston, and it was at a town hall meeting Friday in Richardson that he dropped the L-word.

"What they are ... trying to do is re-create the access and reinforce the image that he has that he speaks the truth and is authentic and not overly handled," said Terry Nelson, a GOP strategist who ran McCain's campaign last year before leaving amid a financial crisis and staff shake-up. "If the campaign steps away from who he is, they'll be in trouble."

The Los Angeles Times contributed to this report.