Joe Schwarz had many admirers. And still, the conservative Republican primary voters of Michigan's 7th Congressional District dumped him Tuesday after his first term in Congress. His opponent, Tim Walberg, said Schwarz was too liberal.

Schwarz's endorsements from politicians with decent conservative credentials -- President George W. Bush and U.S. Sen. John McCain to name two -- didn't help.

Nor did Schwarz's credentials -- as a surgeon, Vietnam vet, Battle Creek mayor and long-time state senator.

What may have mattered most in the district stretching from just west of Ann Arbor to Battle Creek was that Schwarz didn't oppose abortion or gay rights or embryonic stem cell research.

Primary voters who tend to be those at the extreme left and right of their respective parties are a tough crowd.

Sen. Joe Lieberman, a moderate Democrat from Connecticut, found out as much Tuesday, too, when his support for the Iraq war led to his defeat in that state's primary.

Why can't voters who are closer to America's middle get more moderates on their November ballots? Because they stay at home in primaries and people who feel more strongly about abortion and other defining issues don't, said experts.

Thanks to them, Walberg and Democrat Ned Lamont in the U.S. Senate race in Connecticut both easily defeated respected, moderate incumbents. And their victories Tuesday had some wondering whether the middle is at risk of disappearing from politics altogether.

"It seems pretty clear that the extreme right wing was highly motivated and turned out," said Phil Power, founder and president of the Center for Michigan, a moderate think tank in Ann Arbor. Schwarz spoke at the group's March conference on the state's economy. "Moderates had a real opportunity to re-elect a guy of great stature and credentials, but they didn't turn out."

The $1.1 million the conservative Club for Growth spent backing Walberg helped, too, Power said. Walberg had $273,000 on hand has of July 19, according to federal campaign records. Schwarz had $221,000 as of that date, records show.

"A lot of folks are dismayed that the country looks that it's being run by extremists on both the right and the left," Power said.

The Schwarz and Lieberman losses show "It's getting tougher and tougher for candidates to get past the litmus test of the parties," said Bill Rustem, of Public Sector Consultants in Lansing. "The Lieberman and Schwarz examples show it's tough to be a moderate and get through a primary."

But calling losses by moderates in primaries a triumph of extremism and a peril to democracy is simplistic, said Bill Ballenger, publisher of Inside Michigan Politics.

Primaries attract mainly the fringes of both parties, Ballenger said. "The idea that the wacko, right wing loonies came out of the woodwork to knock off Joe Schwarz is crazy," Ballenger said. "They're the same people who voted two years ago" when Schwarz won a six-way Republican primary with less than a third of the overall vote against five more-conservative candidates.

Walberg said his values are a better fit for the district and called the 2004 election an aberration where conservative candidates split the primary vote.

Jobs, the economy and immigration were among the discussions, "but it was about traditional values, too," said Walberg, a Tipton preacher. "We talked about life and marriage."

Smart, affable and a longtime media favorite, Schwarz was viewed as effective by Lansing and Washington insiders.

But the primary voters and activists are less insiders than true believers -- on the Republican side about low taxes, limited government and social conservativism. Democrats at the moment are rallying around anti-Republicanism and, for Lamont in Connecticut, a change of course on Iraq.

Schwarz didn't hesitate to express his disdain for the true believers. Three weeks before the primary he voted against a proposed amendment to the Constitution to define marriage as exclusively between one man and one woman, a position that put him on the wrong side of most of those who voted in Tuesday's GOP primary in his district.

On Wednesday, Schwarz said he's proud of his record and has no regrets about running a campaign in which he hoped to persuade independents and Democrats to vote in the GOP primary.

"I look at this election as probably a victory for right-to-life, anti-abortion, anti-embryonic stem cell groups but it's a net loss for the Republican Party because it just pushes the party farther to the right," Schwarz told the Associated Press.

Schwarz said he had been contacted by several dozen supporters suggesting he follow Lieberman's path and run in the general election as an independent. He called the idea "intriguing," but said he is not interested.

Under Michigan election law, he couldn't run as an independent anyway, leaving an impossibly daunting write-in campaign as the only alternative.

Schwarz said he's going to spend a week in Montana, where he owns a ranch, before coming back to work and pondering what's next. At 68, he could retire, but said he is "too competitive for that. I still want to kick some ass."