KANSAS CITY, Mo. — Missouri’s U.S. Senate race is shaping up as one of stark contrasts — and a dream matchup for both Democratic Sen. Claire McCaskill and her newly minted Republican challenger, U.S. Rep. Todd Akin.

Within hours of Akin winning the Republican nomination, McCaskill was casting him as a conservative extremist who would jeopardize seniors’ health care and retirement savings while putting college out of reach for all but the rich. Akin countered by portraying McCaskill — one of the most vulnerable Democratic incumbents in the nation — as a budget-busting, tax-hiking, big-spending liberal.

The clash of ideals is welcomed by both candidates. In fact, McCaskill’s ads highlighting Akin’s conservative credentials helped persuade some people to vote for Akin in Tuesday’s primary against self-financing businessman John Brunner and former Missouri Treasurer Sarah Steelman, who had been endorsed by Sarah Palin. Akin won 36 percent of the vote, compared with 30 percent for Brunner and 29 percent for Steelman.

McCaskill, who was unopposed in the Democratic primary, immediately began targeting Akin for the November general election by using his own words against him. She launched a website Wednesday featuring video clips in which Akin expresses opposition to federal student loans and the minimum wage, says he doesn’t like the Social Security program and supports changes to Medicare that could include vouchers for people to buy insurance policies.

“Todd Akin is out of the mainstream,” McCaskill said as she kicked off her campaign with a news conference at a Kansas City sheet metal fabricator. A sign touting her as “a senator on our side” was propped on a raised forklift.

“We’re going to prove to Missourians that Todd Akin is out of touch with their problems, out of touch with the pain that they feel, and out of touch with the views that they hold dear,” she said.

Akin contends it is McCaskill who is out of touch — and to the left — of most Missourians. His prime example: McCaskill’s support for President Barack Obama’s health care law, which received a symbolic vote of disapproval when Missourians passed a 2010 ballot measure rejecting government mandates for people to have health insurance. Akin wants to repeal the federal health care law.

Akin also accuses McCaskill of voting “to bust the budget” by backing Obama’s 2009 stimulus act and says she supports “job-killing red-tape regulation,” although he doesn’t go into a lot of specifics.

“If she’s a moderate, I sure don’t want to run into a liberal,” Akin said in an election night interview with The Associated Press. An Akin spokesman said the candidate planned no public events before ramping up his campaign again next week.

While Akin replenishes his campaign account, conservative groups are keeping the pressure on McCaskill.

Crossroads GPS, which has ties to Republican strategist Karl Rove, launched an $874,000 TV ad buy Wednesday claiming that McCaskill voted repeatedly for higher taxes. It particularly notes her support of the federal health care law, which includes a tax penalty for people who don’t have health insurance beginning 2014. The conservative group now has spent $4.6 million on ads against McCaskill since last year.  

McCaskill countered that “Crossroads is distorting my record.” Echoing a campaign theme of Obama and other Democrats, McCaskill said Wednesday that she supports tax cuts that focus on the middle class and exclude the wealthiest Americans. She also defended the health care law.

“I believe that the health care reform will make things better for Missouri families, if they will give it a chance,” she said.  

In the final weeks before Missouri’s primary, McCaskill ran TV ads criticizing all three leading Republican challengers. But the ads were harsher on Brunner and Steelman than on Akin, causing some to believe that McCaskill was intentionally aiding Akin in hopes of facing him in the general election.

“I believed Todd Akin had a chance of winning, and I wanted to make sure voters understood how conservative he was,” McCaskill told the AP.

McCaskill’s ad highlighted Akin’s conservative viewpoints. It called him a “crusader against bigger government,” asserting that he wants to eliminate some federal agencies and privatize Social Security and noting that he promotes a “pro-family agenda.” It ended with the claim that Akin “is just too conservative.”

Some Republican voters, including tea party activists, told the AP that the ad helped persuade them to support Akin. Others pointed to Akin’s own ads featuring praise from former Arkansas Gov. Mike Huckabee, a Baptist minister and 2008 presidential candidate who now is talk show host.

Akin distributed campaign brochures at churches emphasizing his Christian faith, the Huckabee endorsement and Akin’s strong rating by Missouri Right to Life.

By nominating Akin, Missouri Republicans sacrificed the potential to run an outsiders’ campaign against McCaskill. Akin, 65, is a former state lawmaker who first won election to the U.S. House in 2000, arriving in Washington six years before McCaskill. Akin also has defended his use of so-called earmarks — spending on home-state projects that many in the tea party movement shun — while McCaskill has been a vocal opponent of them.

McCaskill, 59, is seeking a second six-year term in the Senate to cap a lengthy political resume that includes time spent as state auditor, a state lawmaker and a county prosecutor in the Kansas City area