President Barack Obama ramped up his attack Monday on rival Mitt Romney’s venture capitalist record, even as Republicans — and some high-profile Democrats — ripped the incumbent for his “assault on the free enterprise system.” Rising Democratic star Cory Booker, mayor of Newark, New Jersey, fanned the political flames Sunday by denouncing as “nauseating” an Obama ad savaging Romney’s record running private equity firm Bain Capital, then stirred it up further by walking back his own critique. Republicans gleefully jumped on the controversy, highlighting Booker’s remarks as evidence that Obama’s bashing of a cherished free-market ideal is a campaign ploy that does not sit well with many Americans. But amid the political storm, the Obama campaign stepped up the attack on the presumptive Republican nominee’s credentials, unveiling a new video painting Romney as a corporate raider who forced Bain-acquired office products supplier Ampad into bankruptcy and “walked away with” $100 million in profits. “We were making money, and for them to just come out from nowhere and shut the place down — it was devastating,” Jerry Rayburn, who worked at the Indiana factory, said in the video. “To me Mitt Romney takes from the poor and the middle class, and gives to the rich. He’s just the opposite of Robin Hood.” Booker, who describes himself as an Obama surrogate, had barreled into the fray when he called out the president for targeting Romney’s time running Bain. “If you look at the totality of Bain Capital’s record, they’ve done a lot to support businesses,” Booker told NBC’s “Meet the Press” on Sunday. Booker said he was “very uncomfortable” with the attacks as well as with tactics by a conservative group that had planned a race-fueled ad campaign against Obama. Romney repudiated that campaign after the plans were leaked. “This kind of stuff is nauseating to me on both sides,” Booker said. “Enough is enough. Stop attacking private equity. Stop attacking (Obama’s former pastor) Jeremiah Wright.” Booker swiftly went into damage control, taping a brief video in which he reaffirmed support for Obama and said he had merely expressed concern that such negative campaigning risks drowning out debate over more substantive issues like the economy. But even as Booker went on to say he felt that Obama should indeed investigate Romney’s time at Bain, the bell had been struck. Romney’s team pounced on Booker’s original comments as an example of Democratic unease with Obama’s ding on capitalism. “President Obama continues his assault on the free enterprise system with attacks that one of his supporters, Newark Mayor Cory Booker, called nauseating” and a former adviser called “unfair,” Romney campaign spokeswoman Andrea Saul said in a statement. Obama’s policies, she said, “have failed every American who expected their president to focus on the economy and make things better.” The Republican National Committee quickly turned Booker’s comments into an opportunity, launching an “I Stand with Cory” petition taunting Obama’s Democrats while raising campaign funds from supporters. Democratic former congressman Harold Ford Jr complicated matters by going on MSNBC on Monday to say that “I would not have backed off the comments if I were Mayor Booker.” “I agree with him, private equity is not a bad thing,” Ford said. Obama’s ad, which rolls out this week across five swing states, shows former steel plant employees slamming Romney as a “vampire” and “job destroyer” for acquiring their factory, leading it to bankruptcy and walking away with hefty profits. Democrats, like Romney’s defeated rivals for the Republican nomination, have painted the former Massachusetts governor as a poster boy for corporate excess, which many Americans blame for the country’s economic woes. Romney regularly touts his business experience on the campaign trail, and claims to have created 100,000 jobs at Bain, a record he says positions him to reboot the crashed US economy.