Mitt Romney repeatedly seemed to question whether President Barack Obama believed in the American dream in an energetic campaign speech Tuesday, calling his rival's approach to leadership "foreign" and accusing him of trying to change "the nature of America."

"President Obama attacks success and therefore under President Obama we have less success, and I will change that," Romney told more than 1,000 cheering supporters at an oil and gas services company in suburban Pittsburgh, Pennsylvania, after the president told a Virginia audience Friday that all Americans benefit from government investment in infrastructure and education.

Breaking a hiatus of several days without a public campaign event, Romney attacked his rival for what he called Obama's wish to attack individual success and give government credit for the accomplishments of individual Americans.

"It is changing the nature of America, changing the nature of what Democrats have fought for and Republicans have fought for," Romney said, adding: "celebrating success instead of attacking it and denigrating it makes America strong."

"That's the right course for this country," Romney continued. "His course is extraordinarily foreign."

At a campaign event last week, Obama emphasized the role of government in the success of American industry.

"If you've been successful, you didn't get there on your own," Obama told supporters in Roanoke during a rainstorm Friday. "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."

Romney took exception to Obama's words Tuesday.

"It's not like government just provides those to all of us and we say 'oh, thank you government for doing those things,'" Romney said. "We benefit from them and we appreciate the work that they do and the sacrifices that are done by people who work in government. But they did not build this business."

An Obama campaign spokeswoman accused Romney of misrepresenting the president's words.

"As President Obama said the other day, those who start businesses succeed because of their individual initiative -- their drive, hard work, and creativity," said Obama campaign spokeswoman Lis Smith. "But there are critical actions we must take to support businesses and encourage new ones -- that means we need the best infrastructure, a good education system, and affordable, domestic sources of clean energy. Those are investments we make not as individuals, but as Americans, and our nation benefits from them. Apparently Mitt Romney disagrees."