No House Republican enrages the business-friendly wing of the GOP more than Justin Amash. But members and operatives who hoped to end his political career are running out of time and moxie before Michigan’s Aug. 5 primary.

So far, many of Amash’s cash-flush critics have passed on investing substantial resources in his GOP rival, former East Grand Rapids School Trustee Brian Ellis. At the same time, Amash allies such as the Club for Growth and Sen. Ted Cruz, R-Texas, have tangibly backed the libertarian sophomore’s re-election in the 3rd District.

Amash rankles House GOP leadership and rank-and-file members over issues ranging from national security to parochial legislation. He’s often at odds with much of his conference, and privately, many members and their aides say their capacity to govern would be easier if he was no longer in Congress.

But on Capitol Hill, it’s still taboo to try to oust a fellow member — even someone who frustrates GOP Leadership as much as Amash. As a result, almost no one in Congress will publicly challenge his re-election.

For example, Ellis’ sole donor in the Michigan delegation is House Intelligence Committee Chairman Mike Rogers — and he’s retiring this year.

“Brian will be an effective advocate in Washington, not an ineffective, celebrity politician who works against the Republican party at every turn,” Rogers press secretary Kelsey Knight added in a statement.

Ellis’ other congressional donor is Rep. Devin Nunes, a Republican who represents a district more than 2,000 miles away in California. Nunes is at odds with Amash in part because of Nunes’ opposition to water legislation affecting his the Golden State district.

But at least 22 of Amash’s allies in Congress have rallied behind him, including many of his 2010 classmates like Reps. David Schweikert of Arizona, Tim Huelskamp of Kansas, Raúl R. Labrador of Idaho, and Mick Mulvaney of South Carolina.

He boasts additional conservative backers: Cruz, Sen. Rand Paul, R-Ky., and House Financial Services Chairman Jeb Hensarling. Cruz also cut a radio ad that the campaign has used to swamp the airwaves.

The Michigan GOP delegation is sitting on its hands. In a state that boasts four committee chairman, Amash was kicked off the House Budget Committee in 2012.

“There’s not a concerted effort among the Michigan delegation to oust Amash, but there’s not a concerted effort to help him either,” said a Michigan Republican consultant, who was granted anonymity to speak candidly about Amash.

What’s more, members are reluctant to pick a fight with tea party groups by publicly donating to Ellis’ campaign, multiple operatives on Capitol Hill told CQ Roll Call.

Even without congressional help and the traditional PAC donations bestowed on incumbents, Ellis could still spend more than Amash in the race by self-funding. Ellis loaned his campaign $1 million, according to his latest fundraising report, and raised a total of almost $1.7 million.

Ellis is running an organized campaign with a recognized team of consultants. State and national allies insist there is a path to victory — citing local support and low turnout.

The Michigan primary comes in early August, when many of the district’s residence head north for vacation. As a result, Michigan operatives expect only the most passionate and organized to vote.

Ellis has no shortage of gold-standard Republican endorsements in Michigan. He also boasts support from Michigan Right to Life, former Rep. Pete Hoekstra, the Michigan Chamber of Commerce, the Grand Rapids Chamber of Commerce and, most notably, the U.S. Chamber of Commerce.

But as of Friday morning, none of those organizations made a serious financial investment in the race. Fundraising reports did show several pro-Israel groups made significant investments in Ellis’ campaign.

Ellis has one other great hope: The U.S. Chamber of Commerce makes a substantial, last-minute television blitz. The group’s perfect streak of spending in GOP primaries ended Tuesday, when Rep. Jack Kingston, R-Ga., lost the runoff for Senate. The chamber had spent more on Kingston’s bid than any other primary campaign this cycle.

Meanwhile, outside groups have come in big and early for Amash.

The Club for Growth’s independent expenditure arm — which has a mixed record this cycle — is credited with recognizing the Ellis threat early and protecting Amash. They spent $368,000 on the airwaves and bundled $274,000 in contributions for Amash’s campaign, according to spokesman Barney Keller.

“Club for Growth Action’s most recent TV ad buy ended on Monday,” Keller said via email. “We are confident that Congressman Amash is in a very strong position for reelection, but we continue to closely monitor the race, and we might or might not return to the TV airwaves prior to Election Day.”

Americans for Prosperity also made a positive buy for Amash early this year, and Citizens United directly donated to his campaign.

But if Amash wins the GOP primary next week — as most Republicans expect — his Hill adversaries will watch his margin. If he wins by less than 10 percent, and he continues to aggravate his own conference, things might be different next cycle.

“It takes a long time to get people to focus and to be willing to take that plunge, because going against an incumbent is a risk,” the Republican said. ”But given his voting record, in this case, there really is no risk.”

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