Obama justifies focus on Romney's past

Updated at 8:29 a.m. ET.

(CBS News) Despite his campaign having run "a whole slew of positive ads" this cycle, President Obama suggested to "CBS This Morning" co-anchor Charlie Rose, in an exclusive interview, that he's gone negative in his speeches to highlight the "sharp contrast, probably as sharp a contrast as we've seen, philosophically," between himself and presumptive GOP nominee Mitt Romney.

In a clip that first aired Monday on "CBS This Morning," President Obama defended himself from mounting criticism of his campaign's negative attack ads against Romney - particularly on the subject of his time at the private equity firm Bain Capital - arguing that "politics are about choices."

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"We've done a whole slew of positive ads that talk exactly about how we need to change our education system, how we need to change our tax code, how we need to rebuild America, how we need to promote American energy," the president said. "So those just don't get attention in the news."

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But while Mr. Obama views Romney as "a patriot" and loving family man, he said, "he has a particular theory of how to grow the economy that has to do with providing tax cuts for folks at the very top, eliminating all regulations, and somehow that is gonna generate solutions to the challenges we face.

"I've got a very different approach," he continued, "And the more detailed we get into what he's saying and what I'm saying, I think that serves this democratic process well."

"Because politics are about choices?" Rose asked.

"Politics are about choices," the president responded.

Romney blasted the negative rhetoric Monday, saying that the president was simply trying to avoid talking about his record.

"What does it say about a president whose record is so poor that all he can do in this campaign is attack me," Romney said on Fox News.

"I'd say to the president, wouldn't it be interesting Mr. President, wouldn't it be interesting if you spent some time speaking about your record."