MASON CITY, Iowa (CNN) -- As presidential candidate John McCain travels Iowa and New Hampshire on his campaign bus, there's one subject he can't avoid even if he wanted to: Iraq.

Whether it's a moment of silence for the death of a local soldier or a question from the audience, the Iraq war and his unflinching support for it fills the open spaces in his run for the presidency.(Watch Video: McCain won't 'back down,' CNN's Candy Crowley reports)

Traveling through Iowa aboard the bus, the Arizona GOP senator ponders whether his fierce support of the war will hurt his presidential ambitions.

"I don't know and I can't worry about it," he said. "I just won't. There's too many people that have been hurt a lot more than I have as a result of this war. ... You've heard me say this before -- I'd rather lose a campaign than lose a war. ...

"I just have to do what I know is right and articulate what I think is right and best for the country," he added. "This is not a minor issue. It's a huge issue. I articulate what I think has to happen and what will happen if we fail."

Although severely critical of how the war has been conducted, McCain firmly believes the Iraq war has now become part of the broader war on terror.

"The consequences of failure are chaos, genocide and sooner or later we come back, and most importantly, they'll follow us home," he said.

McCain is the war's most visible supporter at a time when only a third of voters think it has been worth the price, both in money and lives lost.

But because of his years as a Vietnam prisoner of war and his staunch support of the military, McCain's strategists believe voters will give him leeway on Iraq.

Whatever happens with the voters, though, he is where he is. In the community centers and town halls of Iowa and New Hampshire, McCain generally enters to the room to the sound of rocker Tom Petty's "I Won't Back Down" -- a campaign promise, of sorts.

"This conflict we are in (is) between good and evil, between the forces of radical Islam extremism that are trying to destroy America and everything we believe in," he said at a campaign stop. "I'm qualified. I know the face of war. I know the face of evil. I will win. We will win, and we will never surrender."