The campaign is also reportedly in talks with NBC and Fox for a similar deal.
Contacted by Horserace, a CBS spokesperson declined to comment on the report. The Obama campaign confirmed the primetime network ad buy, reports CBS News' Maria Gavrilovic, but would not specify which network.
UPDATE: The Obama campaign has now confirmed the report, with spokesman Bill Burton saying the campaign has bought the time from CBS and is negotiating with other networks.
Such purchases are rare in modern politics, though back in 1992 independent candidate Ross Perot, "armed with more than two dozen charts and a metal pointer," made his case in primetime. A 30-minute block on CBS cost the wealthy candidate $380,000, the New York Times reported, and his buy pre-empted the show "Rescue 911."
"In October 1992, Perot drew audiences of 16.5 million and 10.5 million for 30-minute lectures/campaign ad aimed at voters," notes Hibberd. "But in Perot's second run in 1996, the candidate was rebuffed by the Big Four networks in an attempt to sell airtime. The FCC backed the networks in denying Perot airtime, saying that they acted legally in refusing."