The Club for Growth's political action committee announced Wednesday that it will support Rep. Mike Simpson's (R-Idaho) 2014 primary opponent, attorney Bryan Smith.

The conservative PAC is openly soliciting suggestions for which GOP lawmakers it should target in primaries. Smith represents its first crowd-sourced endorsement.

Simpson has a lifetime 58 percent score on the Club for Growth's scorecard -- ranking among the most moderate Republicans in the House. But he comes from one of the most conservative districts in the country -- one that went 64 percent for Mitt Romney last year.

The Club's effort focuses on Republicans in such districts who are insufficiently conservative, in its eyes.

Club President Chris Chocola said Simpson is an ideal target and that Smith was far and away the most popular choice among the submissions received.

"The highest volume and highest quantity was (Idaho's 2nd district) and Bryan Smith," Chocola told Post Politics. "There were too many to ignore."

Since being elected in 1998, Simpson has never taken less than 62 percent of the vote in the general election. In 2012, he easily turned aside a primary challenge from tea party supporter Chick Heileson, 70 percent to 30 percent.

But Simpson had one of the worst primary showings among incumbents in the tea party-dominated election of 2010, taking 58 percent of the vote against three candidates.

Simpson's primary opponents, thus far, have been under-funded -- something the Club's endorsement will help Smith avoid.

Smith announced last week that he raised $147,000 in one month as a candidate -- a strong haul for a primary challenger in a small state. Simpson, a close ally of House Speaker John Boehner (R-Ohio), announced Wednesday morning that he raised $300,000 in the second quarter -- also a good haul.

Smith is a commercial, personal injury, insurance and construction lawyer from Idaho Falls.

It's rare for House incumbents to lose primaries, but conservative groups have increasingly trained their sights on insufficiently conservative Republicans. The Club for Growth was an early player in this game, targeting moderate senators including then-Republican Sen. Arlen Specter (R-Pa.) and former senator Robert Bennett (R-Utah), who was unseated in 2010.