A video featuring Mark Block, campaign manager for Republican presidential candidate Herman Cain, blowing smoke while the song I Am America is heard in the background is generating a buzz on the Web.

In the ad, Block extols his candidate's virtues in extreme close-up. The most-talked about moment arrives near the end of the spot, when Block concludes his endorsement, takes a deep drag on a cigarette and then exhales, as the song I am America swells on the ad's soundtrack before a final cutaway to a smiling Cain.

The ad, which reportedly appeared on Cain's YouTube channel Oct. 19, is generating a lot of discussion this week, with commentators weighing in on its effectiveness.

The ad begins with Block giving a passionate speech about why he became Cain's chief of staff.

Block, who joined the campaign in January from Americans for Prosperity, states, I really believe that Herman Cain will put 'united' back in the United States of America, and if I didn't believe that, I wouldn't be here.

Check out the video here.