WASHINGTON (AP) ― Republican presidential challenger Mitt Romney was in a fighting mood Tuesday after being on the defensive for days, declaring that President Barack Obama had insulted the business community. A key Romney supporter questioned Obama’s patriotism.

The former Massachusetts governor was intensifying attacks to counter blazing political assaults on his history as the head of a private equity firm and his refusal to release more of his tax returns, as other presidential candidates traditionally have done. Democrats and a growing number of Republicans, have urged Romney to release more of his tax records.

Obama has been trying to keep Romney focused on matters other than the sluggish recovery from the 2008 financial meltdown, even releasing a single-shot TV ad Tuesday that suggests Romney gamed the system so well that he may not have paid any taxes at all for years. Polls show the economy is uppermost in the minds of voters who will go to the polls in November.

As the campaign’s tenor grew combative, Romney seized on comments Obama uttered while campaigning in Virginia last week. The president, making a point about the supportive role government plays in building the nation, said in part: “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.”

Obama later added: “The point is, is that when we succeed, we succeed because of our individual initiative, but also because we do things together.”

The challenger pounced.

“To say that Steve Jobs didn’t build Apple, that Henry Ford didn’t build Ford Motors, that Papa John didn’t build Papa John Pizza ... To say something like that, it’s not just foolishness,” Romney said from a campaign rally in the warehouse of a gas and oil services company outside Pittsburgh. “It’s insulting to every entrepreneur, every innovator in America.”

Romney added: “I tell you this. I’m convinced that he wants Americans to be ashamed of success.”

The Obama campaign said Romney had distorted Obama’s message by taking him out of context. Obama’s intended point ― one he made again in Texas on Tuesday ― was that government plays a role in helping people and businesses succeed by building roads, hiring teachers and firefighters, and looking out for the public good.

“There are some things we do better together,” Obama said in San Antonio at the start of a lucrative fundraising day in Texas. “We rise or fall as one nation. That’s what I believe. That’s what our history tells us. That’s what our future demands.”

During the new line of attack, Romney’s campaign also questioned Obama’s patriotism. Former New Hampshire Gov. John H. Sununu, a Romney surrogate, told reporters that businesses that grow from the ground up made the U.S. economy the envy of the world. “It is the American way, and I wish this president would learn how to be an American,” he said.

Asked to clarify that incendiary remark, Sununu later said: “The president has to learn the American formula for creating business.” Still later, Sununu told CNN he had made a mistake. “I shouldn’t have used those words. And I apologize for using those words.”

Romney was campaigning in Pennsylvania, one of the 10 or so states that likely will determine the outcome of the election. Florida is another, and the Obama campaign said Tuesday that the president would make a two-day campaign swing there Thursday and Friday.

As promised, Romney stepped up his criticism of Obama in Pennsylvania, which has been a tough presidential battleground for the Republican Party. He accused Obama of engaging in cronyism, citing federal grants and loan guarantees to alternative energy companies run by Obama backers and donors.

As Romney exhorted supporters in Pennsylvania, Obama was looking to keep the issue of Romney’s business record and finances at the forefront as he raised campaign money in Texas. He is hoping to raise at least $4 million from gay, Latino and wealthy donors.

In Texas, Obama faces a state that has not voted Democratic in a presidential contest since 1976. But Texas ranks among the states with the largest concentrations of wealth, along with New York, California, Florida and Illinois.

The Obama camp aired an ad in the Pittsburgh media market taking issue with Romney’s decision to only release two years of his personal tax returns, a full record from 2010 and an estimate for 2011. That breaks with the custom of past candidates, dating back to his father, George Romney. He set the standard in 1968 by releasing tax returns for 12 years.

In an online editorial, the conservative magazine National Review urged Romney to release additional tax returns even though it agreed with him that the Obama campaign wanted the returns for a “fishing expedition.”

The Obama campaign has also hammered at Romney’s business record, especially discrepancies over when he departed as chief of the private equity firm Bain Capital that he co-founded in the 1980s. Romney says his business record is his chief qualification to be president, and it is the source of his vast fortune, estimated at a quarter of a billion dollars.

Obama continues to try to undermine public support in Romney’s business credentials and trustworthiness. In an interview, Obama defended his targeting of Romney and Bain, saying the public should know if some companies taken over by Bain at any time sent jobs overseas.

“That is hardly a personal attack. That goes to the rationale for his candidacy,” Obama said in an interview with a Cleveland television station that aired Tuesday morning.