The Club for Shrinkage?

The Club for Growth's successful round of Republican primary victories is backfiring in Colorado, as a retiring Republican mulls an independent write-in bid to squelch the CFG candidate who would replace him.

Rep. Joel Hefley is seriously considering running as a write-in
candidate to retain his seat rather than risk handing it over to
Republican nominee Doug Lamborn.

…

Shortly after announcing he would not seek an 11th term, Hefley
endorsed [former aide Jeff] Crank. Crank and Lamborn engaged in a bloody political battle
that included third-party mailings accusing Crank of being a tax hiker
and an advocate for the "radical homosexual lobby," charges Lamborn
either leveled or refused to renounce.

Lamborn, a state senator, won the primary by 892 votes and
is set to face Democrat Jay Fawcett in a district that leans heavily
Republican. Thirteen Republicans have publicly announced their support
for Fawcett, and others have complained behind the scenes about
Lamborn's primary campaign.

Living last year in Virginia I saw this happen on a smaller scale. Conservative Republicans primaried a number of moderate, squishy Republican state legislators in the DC suburbs and exurbs, in large part because of anger over Gov. Mark Warner's tax hikes (which said legislators supported). The victorious conservatives got summarily creamed by Democrats. Colorado-05 should be a safe GOP seat, but Kos, for one, is bullish about Democratic chances in a three-way race. And think how happy Kos et al will be if the CFG primaries Lincoln Chafee.