The picture showed a beaming Obama alongside Ortiz, holding a Red Sox jersey presented by the team.

New York - The latest pitchman in Samsung's marketing machine: an unwitting President Barack Obama.

Boston Sox baseball player David Ortiz snapped a selfie with the president at a White House event using a Samsung phone and tweeted it to his followers on Tuesday.

It was resent by tens of thousands on Twitter. Samsung retweeted the photo as an ad.

The White House press secretary says Obama was not aware of the marketing stunt. Ortiz's agent did not respond to questions.

Samsung, the world's largest maker of smartphones, has a deal with Ortiz.

In its latest fiscal year, the company spent roughly $4-billion on advertising, about four times as much as its top rival, Apple. - Sapa-AP