Kiichiro Sato/AP

At the close of the NATO Summit , taking questions from reporters, President Obama launched his most direct attack yet at challenger Mitt Romney, defending his campaign's attacks on Romney's tenure at Bain Capital and full-throatedly saying "this is what this campaign is going to be about."

"If your main argument for how to grow the economy is 'I knew how to make a lot of money for investors' than you're missing what this job is about," the president said.

In recent days, some of the president's allies - Newark Mayor Corey Booker , former White House 'auto czar' Stephen Rattner - have criticized the Obama campaign's attacks on Bain Capital, the private equity firm Romney headed.

"I think it's important to recognize that this issue is not a quote distraction," the president said today. "This is part of the debate that we're going to be having in this election campaign about how do we create an economy where everybody, from top to bottom, folks on Wall Street and folks on Main Street, have a shot at success. And if they're working hard and they're acting responsibly that they're able to live out the American dream."

The president said that his personal view of private equity firms is that "it is set up to maximize profits and that's a healthy part of the free market, that's part of the role of a lot of business people. That's not unique to private equity. And as I think as my representatives have said repeatedly and I will say today, I think there are folks who do good work in that area and there are times where they identify the capacity for the economy to create new jobs or new industries."

But, the president said, "understand that their priority is to maximize profits. And that's not always going to be good for communities or businesses or workers. And the reason this is relevant to the campaign is because my opponent, Governor Romney, his main calling card for why he thinks he should be president is his business experience. You know, he's not going out there touting his experience in Massachusetts. He's saying 'I'm a business guy. I know how to fix it.' And this is his business."

When one is president, Mr. Obama said, "as opposed to the head of private equity firm, then your job is not simply to maximize profits, your job is to figure out how everybody in the country has a fair shot. Your job is to think about those workers who get laid off and how are we're paying for their retraining…. My job is to take into account everybody not just some. My job is to make sure the county is growing, not just now, but 10 years from now and 20 years from now. And so, to repeat, this is not a distraction, this is what this campaign is going to be about."

-Jake Tapper and Mary Bruce