Halfway through the 2006 primary season, it's pretty clear that something unusual is happening: Lots of state legislators are losing their bids for renomination--17 of them in the "Pennsylvania massacre" in May, for example, and 11 more on June 6. The total for the year so far is over 40. With two dozen primaries still to come, it's possible the ranks of the rejected could grow to nearly 100 before the general election takes place.

Some perspective is in order. While those 40 or so incumbents were losing this spring, well over a thousand were winning, most of them with either token opposition or no opposition at all. It's not as if legislators are dropping like flies. Still, 40 defeats in just a couple of months is a strikingly high number. The only time you expect to see that is in a redistricting year, when large numbers of House and Senate members are thrown into new constituencies or are forced to run against each other. Otherwise, barring age-related decline, ethical misconduct or an unforgivable political blunder, legislators almost never lose primaries.

So why are they losing them this year? One explanation comes to mind right away: It's an uprising against the political status quo. Voters are in a throw-the-rascals-out frame of mind, one might argue, and they aren't waiting until November to express it.

But while that sounds plausible enough, the numbers don't really bear it out. A broad-based anti-incumbent tide should strike both parties in reasonably equal measure, and this one isn't doing that. Democrats have gotten off relatively lightly. Of the legislators defeated so far, three-quarters have been Republicans. That sounds like too much of a tilt to be coincidental.

In fact, it's not coincidental at all. What we're seeing is moderate Republicans being picked off by organized conservative opposition. That was conspicuously true in the voting on June 6, which brought defeat to two incumbents in Montana, three in Iowa and four in South Dakota.

Bernie Olson, a member of the Montana House of Representatives, is a perfect example. That chamber was evenly divided during the last legislative session, 25-25, and each party needed all the votes it could muster. When the Democrats brought out a bill to add $190 million to the state budget for school operating costs and teacher salaries, Olson cast the only Republican vote in favor of it, guaranteeing its passage. In doing so, he was also guaranteeing himself a primary challenge from Mark Blasdel, an activist in the national Young Republican organization who denounced him for insufficient party loyalty and defeated him by a margin of nearly 2 to 1.

Neighboring South Dakota saw a more thoroughgoing purge of Republicans who had opposed the strict anti-abortion bill passed by the legislature this year. While it can be misleading to portray right-to-life issues in strict ideological terms, the four GOP legislators who lost were generally perceived as moderate voices within the state's dominant Republican Party. None of them left any doubt about their feeling that the abortion issue had done them in. "I knew it was political suicide at the time," said one of them, state Senator Clarence Kooistra.

In neighboring Iowa, there was less emotion and no martyrs like Olson or Kooistra. What took place there was a surgically effective campaign by a well-financed pressure group to replace centrist Republicans with conservative activists and move the party caucus significantly to the right.

The three ousted Iowa GOP legislators were state Senator Maggie Tinsman, an 18-year veteran who had supported abortion rights and opposed a constitutional ban on gay marriage; state Representative Joe Hutter, who had opposed an amendment requiring voter approval of state tax increases; and state Representative Paul Wilderdyke, who voted for the tax amendment in the past but said he would not do so again.

All became targets of Iowans for Tax Relief, an anti-tax group whose political influence in the state has come to approach that of the Republican Party itself. ITR has knit together an effective coalition that includes gun owners and Christian right activists as well as anti-tax crusaders. Through its political arm, Taxpayers United, it spent $20,000 on the challenge to Hutter, according to the Des Moines Register, and $15,000 against Wilderdyke. That's a lot in rural Iowa, where the number of votes cast in a state House primary is normally very small. Matt Windschitl defeated Wilderdyke by an unofficial count of 914 votes to 607; on such a small playing field, $15,000 spent wisely can go a long way toward determining the result.

That particular primary also helps to illuminate just what this Midwestern Republican warfare is all about. Wilderdyke was no liberal: A retired Navy officer, he took a pro-life stand on abortion and favored a rebate fund to give surplus state dollars back to the taxpayers each year.

But Windschitl still managed to run against him from the right. A Marine reservist who served in Iraq and the owner of a gun business called Double Barrel Shooters Supply, he took orthodox conservative stands on every subject he discussed. Most important, he promised to support public votes on revenue increases--the one subject that his backers at Iowans for Tax Relief cared about most.

The three Republicans who lost in Iowa were by no means the only ones who had alienated the state's militant right, but they were ones that a clever conservative strategist could single out as relatively cost- free targets. There is virtually no chance that any of these districts will elect a Democrat in the fall; two of the three don't even have a Democratic candidate this year. So no matter what happened, the precarious Republican hold on the House (51 to 49, at the moment) wouldn't be directly affected.

The results of June 6 paralleled what has been happening in state primaries all spring: Vulnerable centrist Republicans have been targeted and taken out by challengers from the more activist right.

In some cases, the campaign rhetoric has focused on issues of short- term intensity and masked the ideological significance of what was going on. The victims in Pennsylvania, as Alan Greenblatt reports elsewhere in this issue, were nearly all incumbent Republicans who had voted for a pay raise in the summer of 2005. But the backing for the challenges to these Republicans came largely from right-leaning organizations such as the Club for Growth and the Young Conservatives of Pennsylvania. Some non-partisan good-government groups also participated--even some left-leaning ones--but this was essentially an internal GOP war: The Republican Senate majority leader and president pro tempore both lost their seats, while the Democratic leaders who had been equally involved in the pay raise maneuvering were left unscathed.

Two weeks before the Pennsylvania massacre, Indiana Senate president Robert Garton lost his seat in a Republican primary that involved similar sleight-of-hand. The topic that hit home with voters was Garton's stubborn backing of free lifetime health care for legislators. But the underlying issue was abortion. In the closing hours of this year's legislative session, Garton declined to push for a vote on a bill that would have required women seeking abortions to be told that a fetus may feel pain. The chairman of the Indiana Right to Life PAC complained that Garton "went out of his way to placate a group of over one dozen moderates in the Senate caucus." And when the primary was held May 2, Garton lost decisively to Larry Walker, a challenger who is militantly anti-abortion and pro-gun and is active in the home-schooling movement.

As with the Iowa primaries, there won't be any change in party representation. Garton's district is heavily Republican, and Walker should win easily in the fall. The question is what effect all of these events might have in the larger contest for party control, in Indiana, Iowa and elsewhere in the country.

In the long run, there are bound to be consequences. If you want to see some, you might look at Kansas, where the most startling political news this spring was the announcement by Mark Parkinson, the former chairman of the state Republican Party, that he was leaving the GOP to run for lieutenant governor on the ticket of incumbent Democratic Governor Kathleen Sebelius. In terms of internecine rivalry, Kansas is far ahead of Iowa. For nearly a decade, there have really been three parties there: the minority Democrats, the hard-right, social-issue Republicans, and the moderate business-oriented Republicans, centered in suburban Johnson County.

The Republican right has won most of the battles, especially at the district level, has made itself the dominant bloc in the legislature and shows no signs of erosion there. But it suffered a painful defeat in 2002 when Sebelius took advantage of the GOP divisions to win the governorship; it will almost certainly suffer another one next year when she and Parkinson form what will essentially be a fusion government; and it faces a difficult struggle in November to reelect its most visible social-issue champion, attorney general Phill Kline. When you think of the Republicans in Kansas, the phrase "pyrrhic victory" somehow leaps to mind.

Is it possible that Republicans have been reenacting the Kansas scenario in all those other states this year--fighting so many battles that they aren't in shape for the war? We should be able to answer that question this November.Is it possible that Republicans have been fighting so many battles that they aren't in shape for the war.