JEFFERSON CITY, Mo. -- Missouri has some proud members of Congress these days.

U.S. Rep. William Lacy Clay, a Democrat from St. Louis, is happy he was rated the most liberal lawmaker in the House. U.S. Rep. Blaine Luetkemeyer, a Republican from the rural central Missouri town of St. Elizabeth, is lauding his distinction as Missouri's most conservative representative. And U.S. Sen. Claire McCaskill, a Democrat from suburban St. Louis, is touting the fact that she ranks smack dab in the middle on the liberal-to-conservative scale.

Three politicians, pleased for three opposite reasons -- all from the same state.

Heading into the 2012 elections, there is perhaps no better example of the diversity and complexity of Missouri politics. The reaction to the recent rankings by the National Journal illustrate why Missouri has been a historical swing state -- with two camps on the extremes of the ideological spectrum, and a core of persuadable people in the middle who tilt statewide elections to either the Republicans or Democrats, depending on the prevailing sentiment.

States such as Ohio and Florida are similar in that regard and, because of their larger populations, carry greater national weight. But many other states are more uniform. In neighboring Kansas, for example, the entire congressional delegation ranks on the conservative side. The Massachusetts delegation is tilted heavily toward liberalism, with the lone Republican -- Sen. Scott Brown -- ranking as the third least conservative Republican in the Senate behind only his two colleagues from Maine.

Rather than being out of step, Missouri's lawmakers on the far left and right more likely are representing the constituents they serve.

Clay's 1st Congressional District, for example, is so heavily Democratic that the winner of an August primary between Clay and U.S. Rep. Russ Carnahan -- who is challenging Clay because his current 3rd District was carved up and reassigned after the 2010 census -- is likely to walk to victory over any Republican opponent in the November general election.

As Carnahan filed his candidacy papers this past week, Clay was touting his top liberal ranking as an indicator that he is "a real progressive with a backbone" and Carnahan was something less.

"My voting record reflects more of the progressive views and opinions of a majority of the people who elect me to represent them," Clay said.

Luetkemeyer barely edged out U.S. Rep. Billy Long, a Republican from Springfield, to lay claim to the title as the most conservative Missouri lawmaker in the National Journal rankings. But he viewed it as a victory worth touting.

"The swing right now across the country, and especially in Missouri, is for a conservative point of view in how you look at government," said Luetkemeyer, expressing confidence in his re-election chances, even though his newly reshaped district contains more of suburban St. Louis than before.

One reason that many members of the U.S. House can safely boast of their conservative or liberal credentials is that a majority of districts are drawn so as to be relatively safe seats for incumbents -- with voters who tend to lean either Republican or Democratic.

But it becomes less appealing in a statewide election in a swing state such as Missouri for candidates to cast themselves as either an extreme conservative or extreme liberal. That is especially true for liberals in Missouri, where the state has recently leaned to the right.

That helps explain why Republicans have been highlighting McCaskill's ties to Democratic President Barack Obama and some of his policies.

It also explains why McCaskill was quick to put out a press release noting she ranked "exactly in the moderate middle" among senators in the National Journal chart, which categorized officeholders based on votes on economic, social and foreign-policy issues.

"I haven't made folks on either extreme of the political spectrum happy, but I think that means I'm probably doing something right," McCaskill said in her press release.

Because of Missouri's diverse liberal-to-conservative electorate, McCaskill "kind of has to win both of those audiences -- or at least not lose them," said Tobias Gibson, an assistant political science professor at Westminster College in Fulton.

In that sense, Missouri's political diversity remains "a microcosm of what's happening nationally," where "things are really up in the air," said Elizabeth Paddock, chairwoman of the History, Political Science and Geography Department at Drury University in Springfield.

"Missouri has always had that sort of split personality. Where is Missouri? Is it in the South? Is it in the border South? Is it in the Midwest? Is it in the plains?" Paddock rhetorically asked. "I think the actual physical geography of Missouri illustrates -- or plays to -- its political geography as well."

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EDITOR'S NOTE: David A. Lieb has covered state government and politics for The Associated Press since 1995. He can be reached at http://twitter.com/DavidALieb.