Rep. Mike Simpson (R-Idaho) has defeated his Tea Party challenger, winning a high-priced proxy war between establishment and conservative groups.

The Associated Press has called the race for Simpson, who was leading attorney Bryan Smith (R) by 63 percent to 37 percent with 25 percent of precincts reporting.

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Simpson, a close ally of House Speaker John Boehner John Andrew BoehnerLongtime House parliamentarian to step down Five things we learned from this year's primaries Bad blood between Pelosi, Meadows complicates coronavirus talks MORE (R-Ohio), was a top target of the fiscally conservative Club for Growth. The organization spent more than a half-million dollars seeking to topple him, and helped bundle hundreds of thousands more to Smith.

But Simpson took his challenge seriously, raising huge sums of his own and benefitting from more than $2.5 million in outside spending. He went on air early to attack Smith as an amoral "trial lawyer" and debt collector, effectively damaging him as a messenger before Smith had the campaign funds to fire back.

The U.S. Chamber of Commerce, the National Rifle Association, Defending Main Street Super PAC, the National Association of Realtors, the American Dental Association were the heaviest hitters on Simpson's behalf.

A Chamber ad featuring former presidential nominee Mitt Romney, who's very popular in the heavily Mormon district, helped boost Simpson, and the NRA's seal of approval helped shore up his standing with conservatives.

Smith and the Club attacked Simpson for supporting the Wall Street bailout and and backing earmarks, and in the final days Smith accused him of supporting "amnesty' immigration legislation. But the Club for Growth admitted defeat a few weeks ago, shifting resources out of Idaho at the end of April to focus on other races.