Earlier Tuesday, McCaskill's campaign website debuted an ad citing comments Akin made over the past year expressing dislike for Social Security, questioning the constitutionality of the Medicare program and voicing opposition to the federal government's role in setting a minimum wage and financing student loans.
The ad culminates by referencing Akin's remark about rape and asks: "What will he say next?"
McCaskill's campaign said the ad is running on TV stations statewide.
It marks the first time McCaskill has addressed Akin's rape remark in an ad, though she has cited his comments about other issues from the moment he won the Republican primary. As the drop-out deadline passed Tuesday, McCaskill also launched a new online fundraising drive with the declaration: "Todd Akin is Officially Claire's Opponent."
After his rape remark, Akin lost the financial support of the Republican National Committee, the GOP's Senate campaign arm and the Crossroads group affiliated with Republican strategist Karl Rove. That eliminated millions of dollars of planned advertising in Missouri.
Akin has countered that with a small-dollar, online fundraising drive highlighting how he's standing up to Republican Party bosses and President Barack Obama's administration. Former Republican presidential candidate Newt Gingrich headlined a more traditional fundraiser Monday for Akin. And late Tuesday,
And late Tuesday, Missouri U.S. Sen. Roy Blunt changed course by saying he was supporting Akin — whom he'd called on to quit the Senate race last month in a joint statement with four former Missouri senators.