Eager not to cede ground in the debate over the economy, President Obama will offer his first direct response Friday to rival Mitt Romney’s escalating assault on his commitment to business and free enterprise, a senior campaign official said.

Obama will use speeches in Fort Myers and Orlando to fight back against the presumptive Republican nominee, who for several days has lambasted the president for using the phrase “you didn’t build that” during a campaign event last week, while talking about business owners.

“Somebody helped to create this unbelievable American system that we have that allowed you to thrive,” Obama said during a rally in Virginia on Friday. “If you’ve got a business, you didn’t build that.”

Republicans have seized on the phrase to make the case that Obama prefers big government to free-market capitalism and entrepreneurship. Romney’s campaign released a Web video mocking the president, and the presumptive GOP nominee chided Obama again Thursday during an appearance in Roxbury, Mass.

But the fuller context of the remarks make it appear that the president was arguing that the government helps the private sector by building the roads, bridges and education system that businesses rely on. Until now, the president has been content to let his aides rebut the Republican criticism, but aides said he is ready to fight back, perhaps an indication that the GOP attacks are starting to worry the Obama campaign.

“Expect President Obama to counterpunch Mitt Romney’s out-of-context attack on businesses tomorrow,” said the campaign official, who spoke on the condition of anonymity to discuss internal strategy.

The official added that Obama also will highlight ways in which Romney’s economic agenda, which the president has equated to trickle-down economics, would be “devastating for small businesses.”

Obama will “talk about his longtime belief in the drive and ingenuity of the American worker and his ongoing commitment to ensuring entrepreneurs and small businesses have the tools they need to succeed,” the official said.