A new national television advertisement released by President Obama’s campaign and slated to air during the opening ceremony of the 2012 Olympic Games features the Democratic incumbent delivering an impassioned stump speech in which he ties national prosperity to the success of the middle class.

“I believe in fighting for the middle class because if they’re prospering, all of us will prosper,” Obama says in the 30-second advertisement, part of a $6 million Olympics ad buy, NBC confirmed. “That’s the idea of America and that’s why America is the greatest nation on earth.”

As Obama speaks, a montage shows “workers and doers and dreamers,” including a farmer loading hay into a pick-up truck, a woman punching in for her shift, and a suit-wearing father coming home to his family. The advertisement, which does not mention Mitt Romney, is a departure from a series of negative ads that criticized the former private equity executive’s business record and resistance to opening up his personal finances to increased scrutiny.

“Obama’s statement is a broad generalization. Real prosperity depends on all economic classes moving upward,” said Robert Kallan, a visiting economics professor at DePaul University, adding that the ad plays to undecided voters, the majority of whom are in the middle class.

The Romney campaign, which has not made an ad buy during the Olympics, NBC confirmed, released a statement on Friday highlighting poor economic numbers, seen as the biggest drag on Obama’s candidacy.