In a single day, Mitt Romney's pit bull, former New Hampshire Gov. John Sununu, called the president stupid, a friend of felons, un-American, a socialist and a stoner; played on birther fears -- and, almost immediately, took it back.

Not all of it, of course. Just the part about wishing the president "would learn to be an American."

Before the day was over, he was apologizing for the comment on CNN.

But, in the famous words of Chief Justice Thomas McBride, you can't "unring the bell."

Even though Sununu backtracked on the "learn to be an American" comment moments after he uttered it, in the world of instant Internet news, it had already lapped the earth a couple of times in the interim.

Some suggested he did it on purpose.

"The Romney campaign has officially gone off the deep end. The question is what else they'll pull to avoid answering serious questions about Romney's tenure at Bain Capital and investments in foreign tax havens and offshore accounts," said Obama campaign spokeswoman Lis Smith. "This meltdown and over-the-top rhetoric won’t make things better -- it only calls attention to how desperate they are to change the conversation."

But those who know his history as a big mouth conservative attack dog know, as The Atlantic's Molly Ball put it so well, "If you want the fire of Sununu's passion, you have to accept a burned-down building every once in a while."

In short, Sununu fires first, asks questions -- or not -- later. And no one is safe. Not even other conservatives. Facing off against Fox News commentator Juan Williams -- yes, the Juan Williams cut loose from NPR for letting his conservative politics infect his reporting -- on Sean Hannity's show, Sununu said: "Don't let your blind loyalty to this president make you sound foolish."

During the primaries, he ripped apart Romney's Republican opponents. In December, he called Newt Gingrich "self-serving." In March, Rick Santorum got a scalding -- Sununu blasted him for his "emotional outbursts."

So when Romney sent Sununu in it's hardly surprising Sununu would unleash a toxic spill at the president. And it's no more surprising that he would go too far.

Among his zingers for the day: "He has no idea how the American system functions, and we shouldn't be surprised about that, because he spent his early years in Hawaii smoking something, spent the next set of years in Indonesia, another set of years in Indonesia, and, frankly, when he came to the U.S., he worked as a community organizer, which is a socialized structure, and then got into politics in Chicago."

OK, that covers stoner and socialist, along with some hints at un-American and stupid. But Sununu isn't one to leave his attacks at mere hints.

He also pointed to Obama's origin in Chicago and its "political-slash-felon environment."

In truth, the president set himself up for the attack. In a speech in Roanoke, Va., Obama made the argument that the infrastructure provided by government is necessary for businesses to succeed.

"If you were successful, somebody along the line gave you some help," he said. "There was a great teacher somewhere in your life. Somebody helped to create this unbelievable American system that we have that allowed you to thrive. Somebody invested in roads and bridges. If you've got a business, you didn't build that. Somebody else made that happen. The Internet didn't get invented on its own. Government research created the Internet so that all the companies could make money off the Internet. The point is, is that when we succeed, we succeed because of our individual initiative, but also because we do things together."

What Sununu, Romney and other conservatives pounced on was the out of context comment, "If you’ve got a business, you didn't build that. Somebody else made that happen."

In a conference call with reporters, set up by Romney's campaign, Sununu said:

"The president clearly demonstrated that he has absolutely no idea how the American economy functions. The men and women all over America who have worked hard to build these businesses -- their businesses, from the ground up -- is how our economy became the envy of the world."

Then came the slip. "It is the American way, and I wish this president would learn how to be an American."

He backpedaled before the call was even over. When someone asked him what he meant, Sununu said, "What I thought I said but I guess I didn't say is that the president has to learn the American formula for creating business. The American formula for creating business is not to have the government create business."

But the horse was out of the barn. Sununu had effectively stirred two key tenets of ultra- conservative anti-Obama sentiment -- 1) he's not really American, and 2) he's a socialist, pushing for government control over society.

And Romney can act like he doesn't necessarily agree with Sununu, but he himself said later in the day, "The course we're on right now is foreign to us. It changes America."

By the end of the day, Sununu was back on his leash.

"I made a mistake, I shouldn't have used those words," he told CNN's Wolf Blitzer. "I'm apologizing for those words, I shouldn't have used them."

And yet another Romney surrogate and potential VP pick, Tim Pawlenty, was trying to distance the campaign from its provocateur-in-chief.

"I think he clarified it," he told MSNBC's Andrea Mitchell. "Obviously, the governor has a knack for colorful language and can be very informative and entertaining."

The real question is whether Obama's campaign folks are right about why. Is it really a sign that Romney will do anything to avoid releasing his tax returns -- even send in Sununu?

By Terra/Carlos Harrison