Over at the Campaign Diaries blog, Taniel wrote a good post on Thursday debunking the “unsubstantiated myth” of a pending primary challenge against Senator Chuck Grassley. Bill “crazier than Steve King” Salier got this speculation going in the spring, when many among the religious right were disappointed by Grassley’s reaction to the Iowa Supreme Court’s Varnum v Brien ruling.

This summer, Grassley continued to disappoint the right by negotiating with other Senate Finance Committee members on health care reform. State Representative Kent Sorenson wrote an open letter to Grassley, pleading with him to provide “principled and bold leadership”. Sorenson’s letter is the most-viewed post ever published on The Iowa Republican blog, where Craig Robinson warned last month,

The longer Sen. Grassley strings along Iowa Republicans, the more difficult his re-election effort may become. At the beginning of the year, it would have been absurd to suggest that Sen. Grassley could face a legitimate primary challenge. Now, with each and every passing day that Grassley flirts with supporting some version of health care reform, the possibility of a primary challenge grows.

Grassley’s conservative critics are misguided in the sense that the senator has done more to block health care reform than move it along. If not for Grassley and the rest of the Finance Committee “gang of six,” Democrats might have been able to get the bill through the Senate this summer.

Still, the disappointment with Grassley is real. The trouble is, you can’t defeat an incumbent just by being mad, and as Taniel points out, no Republican appears likely to run against Grassley in next year’s primary. Salier has ruled himself out, as has Sorenson (though I wish Sorenson would run for Senate, giving Iowa Democrats an open seat target in House district 74).

Social conservatives are likely to focus on the governor’s race between now and June 2010. Bob Vander Plaats will officially announce his candidacy on Labor Day and will need all the help he can get from the religious right if former Governor Terry Branstad gets back into politics. Yesterday Vander Plaats promised to give homeschooling parents and those whose children attend private schools more influence over education policy. If the GOP primary comes down to Vander Plaats against Branstad, education is sure to become an issue, since some Republicans feel Branstad didn’t do enough to fight the teacher’s union or oppose sex education. The Network of Iowa Christian Home Educators is large and well-organized.

Some Iowa legislative districts may also be targeted by social conservatives, if there is an open GOP primary or a Republican incumbent deemed to be doing too little to advance the religious right’s causes. The Iowa GOP is in a bit of a bind; party strategists understand that they should emphasize economic issues, but some social conservatives become angry when Republicans say too little about abortion or same-sex marriage. We saw this dynamic play out in the recent House district 90 special election. Although Republican candidate Stephen Burgmeier toed the line on the so-called “pro-family” agenda, two conservatives ran against him because he wasn’t emphasizing their issues. The two minor candidates received 282 votes combined, while Burgmeier lost to Democrat Curt Hanson by 107 votes.

You can run a statehouse campaign on a shoestring, while taking on Grassley in a GOP primary would be a very expensive hopeless cause. The religious right may give other establishment Republicans headaches next year, but Grassley is home free.