The ads are running on Spanish FM radio stations in Reno and Las Vegas that reach all parts of the state, according to Obama's campaign.

Obama is not the first candidate to air ads targeting Nevada Hispanics. Last month, New Mexico Gov. Bill Richardson had spots on Reno and Las Vegas radio.

Richardson's ads were narrated by the candidate and focused on his resume as a governor, diplomat and congressman. "With great pride and with your help, I hope to be the first Hispanic president," he said in the ads.

Obama has had television ads in Iowa since June and is also airing radio ads targeted at black voters in South Carolina, where they are running on gospel and R&B stations, according to his campaign.

The Nevada ads for Obama, who does not speak Spanish, are narrated by male and female Spanish voices. The female voice begins the ad by saying, "If you don't know who Barack Obama is, let us give you a hand."

The ads appear to start from the premise that Hispanics haven't heard of Obama, then use that to their advantage, said University of Nevada, Las Vegas, political scientist David Damore.

"If they (Hispanics) don't know anything about him, he can paint himself the way he wants to," Damore said. "It's a pretty shrewd move."

The description of Obama is certainly true, if selective, Damore said. Obama's father was Kenyan, and absent; he was largely raised by his white American mother in Hawaii.

"I'm sure somebody would say his life growing up in Hawaii was not exactly like someone coming across the border," Damore said. Similarly, while Obama emphasizes that he is an observant Christian, he is not Catholic like most Hispanics.

Obama's campaign officials wouldn't say Monday how widely or for how long the ads would air. The campaign officials said the ads were part of a broad Hispanic outreach program that also includes targeted canvassing and phone calls as well as Spanish-language campaign literature.

A March poll of Hispanic voters nationwide found New York Sen. Hillary Clinton to be by far their top Democratic candidate. However, the Latino Policy Coalition, which commissioned the poll, noted, "much of the support appears to be based on name identification."