Missouri Sen. Claire McCaskill (D) said she had received the message from her state’s voters after they approved a ballot initiative looking to exempt the state’s residents from mandates contained within the healthcare reform law.

McCaskill said she understood what Missouri voters had been trying to say about the healthcare reform law for which she had voted in the Senate. But the centrist senator downplayed the vote as a result of heavy Republican primary turnout and a lack of education about the effects of the law.

“I certainly noticed the vote on Prop C, the healthcare law, and: message received,” she said Wednesday in a conference call with state reporters.

“I think there has been … a lot of noise about the mandate that people have gotten so focused on that they don’t realize that there’s going to be more access and affordability and more choices,” she said.

The Missouri proposition looks to exempt the state from two key aspects of the health reform law: the mandate that individuals buy insurance and the mandate that businesses provide health insurance to employees or otherwise face a penalty.

Republicans trumpeted the state vote on Wednesday as a sign that the opposition they’ve led to Democrats’ healthcare reform legislation had been successful and would reward their party at the polls this fall.

McCaskill explained her take on the vote:

I know that there’s a lot of work we need to do on not just the provisions of the law, but most importantly making sure everyone knows what’s in the law. And I can only be hopeful that as time goes on, more and more people realize the positive things that are in the bill. I do know that this vote very closely reflected the number of people who voted in the Republican primary versus the Democratic primary. But nonetheless, message received. I appreciate the fact that voters are sending a message. I don’t think it has any impact on the law itself, but it is a message. I wish my Republican colleagues in the legislature would pay as much attention to the message that the voters sent on campaign finance in 2007, as I know they will want to pay attention to this one.

The first-term senator is up for reelection in 2012 in a bellwether state where Republicans have enjoyed some advantages in recent elections. Her vote in favor of healthcare reform could end up becoming a top issue in that cycle, when a number of Republicans are sure to sign onto efforts to challenge her.

In the meanwhile, McCaskill said that she’d be among those looking to respond to developing problems within the reform law, if need be.