The buy represents the first ads run by the state GOP in conjunction with Akin's campaign, with the state party paying for $386,000 of the buy and Akin's campaign making up the difference, Politico reported.
The National Republican Senatorial Committee has declined to comment on whether it is the source of the money used by the Missouri GOP on Akin's behalf. The national committee previously has said it would stay out of the race.
If the NRSC contributed any money to the ad blitz before Election Day, it would mark a marked reversal by Texas Sen. John Cornyn and other Senate GOP leaders who denounced Akin after he said during a television interview in August that women's bodies can shut down and avoid pregnancy after a "legitimate rape."
Cronyn also called on Akin to step aside and GOP strategists said the NRSC would shift its planned $5 million earmarked to help Akin defeat McCaskill to other races.
Politico said only national committees, such as the National Republican Senatorial Committee or the Republican National Committee, or individual campaign committees that raise money in compliance with federal limits can transfer funds to a state party for a coordinated ad buy.
A spokesman for the Missouri GOP declined to comment, saying it would not discuss its advertising strategy. The RNC could not be reached for comment.
As of Sept. 30, campaign filings indicated Akin had $553,000 cash on hand. The Missouri Republican Party had $375,000 available for the Akin buy, its filings indicated.