NEW YORK -- A super PAC working to defeat President Barack Obama is preparing an ad campaign highlighting Obama's ties to his controversial former pastor.

A Republican strategist involved in the planning said conservative billionaire Joe Ricketts wants to bankroll an effort publicizing the racially incendiary sermons delivered by the Rev. Jeremiah Wright at a Chicago church Obama once attended. The sermons drew considerable attention and presented a hurdle for Obama in 2008 as he sought the Democratic presidential nomination.

The Republican spoke on condition of anonymity to discuss private strategy sessions.

The plan would involve at least $10 million in advertising. News of the campaign was first reported by The New York Times.

Republican Mitt Romney refused to answer questions about the effort as he boarded a plane Thursday in Miami.

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