WASHINGTON -- Mitt Romney refused to give the green light Wednesday to a full discussion of his career in private equity at Bain Capital.

Time Magazine's Mark Halperin asked Romney twice whether he would "welcome" a discussion about his time in private equity. After the first question, Romney immediately turned the conversation to President Barack Obama.

"Well of course, I'd like to also focus on his record," Romney said of the president.

After Romney ran through a number of things he disagrees with the president on, Halperin pressed a second time: "But you welcome scrutiny of your business record, is that right?"

Again, Romney did not answer directly, simply going over why his business experience is a better qualification than Obama's time as a community organizer.

"I was astonished at how quickly he pivoted. He never even really answered the question," said Steven Rattner, a former Obama adviser and private equity executive, on MSNBC later in the day.

Rattner has been in the news recently after he criticized the Obama campaign's attack ads targeting Romney's Bain record. He wrote a New York Times op-ed Wednesday backtracking somewhat from his criticism.

There are a few possible reasons why Romney was so squirrelly during his interview with Halperin. Most likely, the biggest is that Romney and Obama are locked in a battle royale to make the election about their opponent and not themselves. So giving an inch and "welcoming" questions and critiques about Bain -- like Romney backer John Sununu, the former New Hampshire governor, did Tuesday -- is, from one perspective, a tactical loss, even if Romney feels confident in discussing the topic.

But another reason may be that once Romney gets beyond the general argument that his time in the private sector better qualifies him to revive the economy, getting specific often means talking about the way the free market works. And that can be a politically difficult topic.

It's not as if Romney doesn't believe in capitalism. He devoted a full six pages in his 2010 book, "No Apology," to describing the merits of "creative destruction."

"It takes a leap of faith for governments to stand aside and allow the creative destruction inherent in a free economy, but it's a leap that has been successfully made by every advanced economy in the world," Romney wrote.

But even in that book, Romney made clear he knows that the idea of allowing businesses to fail, in the belief that a vibrant, innovative economy will produce new companies and more new jobs, can be a challenging argument to sell.

"Unions as well often oppose productivity innovations that will lead to reduced employment; understandably, they aren't persuaded by arguments that workers will eventually find employment in new enterprises," he wrote.

He also noted that the process can "unquestionably stressful -- on workers, managers, owners, bankers, suppliers, customers, and the communities that surround the affected businesses."

On Wednesday, Romney avoided this topic by emphasizing his understanding of the energy sector. And he has talked about the sometimes harsh realities of free market competition before. But as Romney tries to push back the uncaring corporate raider identity that the Obama campaign is trying to foist onto him, he appears to be grappling with how to describe his economic beliefs in a way that does not play into his opponent's hands.