(AP Photo/Jeff Roberson)
Republicans have long looked at Missouri as a winnable state in the effort to gain control of the Senate. Akin, 65, a six-term congressman from suburban St. Louis, won a hotly contested three-way race for the GOP Senate nomination on Aug. 7.
But just weeks later, Akin set off a furor in a televised interview by saying that women's bodies have a natural defense against pregnancy in cases of "legitimate rape." He made the comments when asked whether he supported abortion in cases of rape, and the answer set off a firestorm that prompted key Republicans -- including Senate leaders, the party's chairman and GOP presidential nominee Mitt Romney -- to drop their support.
McCaskill has said little about Akin's comments in the four weeks since he made them, only that Republican voters picked him and he should remain in the race.
Asked at Friday's debate before a gathering of Missouri newspaper editors about whether Akin's remarks had a place in the race, McCaskill, 59, an abortion rights supporter, said the comments "open the window to his views for Missourians." She called many of his views extreme, saying he wants to end federal funding for school lunch programs and privatize Medicare and Social Security.
"It's not what he said that is the problem," McCaskill said. "It's what he believes that is the problem."
Akin responded by saying the election was "not about words. It's about two different voting records that are the exact opposite."
Akin has repeatedly apologized in televised ads about the rape comment and insists he's not leaving the race, even though the gaffe has so far cost him millions of dollars in campaign money.
Despite everything, many still consider Missouri to be a toss-up given the state's increasingly conservative population.
The hour-long debate was largely cordial. Neither candidate interrupted the other. They greeted each other at the start and parted with smiles and brief handshakes.
The two candidates were most at odds over programs for the elderly, sparring over Medicare and Social Security.
Akin criticized Obama's health care plan, which he said cuts $700 million from Medicare while creating a board "that will effectively be the people deciding who gets medical treatment and who doesn't." He prefers a Medicare plan allowing senior citizens to select their own providers.
"The mindset here is that the federal government should do everything for us all the time," Akin said.
McCaskill said any plan to privatize Medicare would limit benefits for seniors.
"He wants to give seniors a voucher, and once you spend your voucher, you're on your own," McCaskill said.
She defended Obama's Medicare plan, saying it "does not cut one dime" in benefits and extends Medicare's solvency for eight years.
McCaskill accused Akin of votes that could create a "triple whammy" for Social Security: privatization, raising the retirement age and lowering benefits.
Akin responded that too much red tape and too many taxes have put the nation in jeopardy, saying "they're basically crushing freedom in America."
On foreign policy, Akin criticized the administration for "weak and vacillating" policies that he said have hurt U.S. allies and helped its enemies. He was critical of Egypt's response to the tension there, saying the U.S. should withhold money for Egypt "until they start protecting our embassy and not fundamentally insulting us by burning our flag."
McCaskill was critical of U.S. spending to develop infrastructure in Afghanistan, saying: "We need to pull that infrastructure money out and bring it back to America, where we need roads and bridges."
Libertarian candidate Jonathan Dine said both parties share in blame for problems in Washington. He said he would oppose reckless spending and earmarks.
"The government should live within its means, just like the people of Missouri," Dine said.