ROCHESTER, N.H. – After coming under attack over his business career and his assertion that he is not a career politician, Mitt Romney aggressively defended his work as a venture capitalist and told voters here Sunday that he personally has worried about being laid off.

 “I know what it’s like to worry whether you’re gonna get fired,” Romney volunteered during a mid-day rally of several hundred inside an ornate opera house here. “There were a couple of times I wondered whether I was going to get a pink slip.”

 Romney’s campaign could not immediately provide any examples of a time when the candidate feared losing his job.

The former Massachusetts governor rarely speaks in detail about his time as co-founder and chief executive of Bain Capital. But with a new online video financed by supporters of former House speaker Newt Gingrich attacking Romney over Bain acquisitions that led to mass layoffs, Romney moved aggressively to place his venture capital career in a more positive light.

 Romney highlighted the firm’s $5 million investment that helped start Staples, the office supplies superstore that today employs some 90,000 people. He noted: “I was there the night we opened the first store. We helped stock the shelves.”

 “For a while I worked in what’s called venture capital,” Romney said. “What is that? Well, we got money from other people and we would use that to help start businesses or sometimes acquire businesses that were in trouble or not doing so well and then try and make it better or get the businesses to grow. And when you have other people’s money and your own invested in something you’re very careful with it.”

 Later, Romney added: “I spent my career in the private sector. I’m not perfect, but I do get it, and I will use what I know to get America to work.”

Romney also moved to deflect criticism from Gingrich and former Pennsylvania senator Rick Santorum in Sunday morning’s debate over his political career. Romney frequently labels his rivals “career politicians” while telling audiences that he only spent four years in government. Of his one term as governor, Romney often jokes, "I didn't inhale."

“Can we drop a little bit of the pious baloney?” Gingrich said in the debate. He referenced Romney's 1994 race against then-Sen. Edward M. Kennedy (D-Mass.). “The fact is, you ran in ’94 and lost," Gingrich said. “That’s why you weren’t serving in the Senate.”

 Addressing the Rochester rally, Romney said he “never imagined” he would run for president.

 “This is just a very strange and unusual thing to be in the middle of,” Romney said. “I mean, I was just a high school kid like everybody else with skinny legs. And, you know, I imagined that I’d be, you know, in business all my career. And somehow I backed into the chance to do this.”

 It was an unusual statement by a candidate who was raised in public life and is seeking the White House for the second time. His father, George, served three terms as governor of Michigan while Romney was a child and ran unsuccessfully for president in 1968.

 Although Romney addressed attacks leveled by his opponents, he did not mention any by name, and kept most of his speech here focused on Obama.

 “I look at these last three years and I just shake my head,” Romney said. “I don’t think the president gets it. I don’t think he gets what’s so unique about America. I don’t think he gets the power of people pursuing their dreams, of the pursuit of happiness as described in the Declaration of Independence. I don’t think he feels it, he experiences it the way so many of you do and I do by virtue of having lived in the real world.”