PORTLAND, Ore. - After ten days of relatively muted response to Mitt Romney's "you didn't build that" attacks, the Obama campaign is now on full-court-press defense, with the president appearing in a new battleground state TV ad to offer a personal rebuttal.

Speaking directly to camera in the 30-second spot, Obama says Romney and Republican ads are "flat out wrong" for taking his words out of context.

"Of course Americans build their own businesses," Obama says,.

"Every day, hard-working people sacrifice to meet a payroll, create jobs, and make our economy run," he says. "And what I said was that we need to stand behind them, as America always has."

For the second time in a campaign ad, Obama is seen sitting in the West Wing office of chief of staff Jack Lew.

The ad buy - running in Iowa, North Carolina, Florida, Ohio, Nevada and Virginia - signals a more aggressive defensive posture by Team Obama as Republicans continue to press their case that the president is anti-business.

"We are not going to stand by while Mitt Romney slices and dices and deliberately takes out of context the President's remarks on businesses," Obama campaign spokeswoman Jen Psaki told reporters aboard Air Force One.

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"Mitt Romney, and his surrogates have tweaked and taken apart to such a degree the President's remarks on an issue he's spoken about many, many times, and Mitt Romney has made similar points, it was important to us to ensure that people knew where the President was coming from, how much he supports entrepreneurs and small business owners, and how their records contrast," she said.

In the past 24 hours, the Obama campaign has produced a flurry of web ads and email statements highlighting how Romney has taken Obama's July 13 comment out of context. The president himself offered a spirited defense of his record toward small businesses Monday night at campaign events in California.

Speaking in Roanoke, Va., earlier this month, Obama pushed the importance of continued government investments in public services and infrastructure that many U.S. businesses rely on to function.

"If you were successful, somebody along the line gave you some help," Obama said. "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."

Republicans have seized on the line "you didn't build that" to claim that Obama was speaking directly to business owners about their businesses.

Responding to the new Obama ad, Romney campaign spokesman Ryan Williams insisted they would not back down. "It's clear what President Obama believes because he told us: 'if you've got a business - you didn't build that. Somebody else made that happen.' He said it, and he meant it," Williams said in a statement.