The Republican establishment is gunning for Justin Amash.

First Bush consigliere Karl Rove slammed the two-term Michigan congressman as the “most liberal Republican.” This would be the same Rove whose ideas for building a permanent Republican majority included the Medicare prescription-drug benefit, No Child Left Behind, and amnesty for illegal immigrants.

Next a group of big-dollar Michigan donors circulated a letter to help Amash’s GOP primary challenger raise funds. The seven signatories, including businessmen Mark Bissell, J.C. Huizenga, and Mike Jandernoa, claimed Amash “and others have effectively nullified the Republican majority in the U.S. House.”

These moves against Amash come as the GOP money men begin to reassert themselves against the Tea Party, withholding support from a controversial Virginia gubernatorial candidate at least in part due his anti-cronyism record. But Amash isn’t a run-of-the-mill Tea Partier.

As big business Republicans converge on Gerald Ford’s old congressional district, the House is on the cusp of forging a bipartisan majority against the unfettered Bush-Obama national surveillance practices that have roiled the country. Amash has been a key leader in that fight.

While some Republican congressmen are pushing to authorize the use of military force against Iran, Amash—a leading opponent of presidential war-making in Libya and Syria and proponent of troop withdrawals from Afghanistan—has been a voice of prudence and restraint.

In a party that has often seemed technologically backwards and out of touch, Amash has gained attention for his prodigious use of social media and detailed explanations of his votes on Facebook. By doing so, the second-youngest House member has pointed the way to greater transparency while making a dent in the GOP’s tech gap.

Only Ron and Rand Paul have more influence with the young libertarian activists entering the Republican Party—a rare bright spot for the GOP in the Virginia governor’s race—than Amash. This is precisely the reason the long knives are out for him.

Rove mocked Amash as a “100 percent, purist libertarian” who votes with Nancy Pelosi when he doesn’t get his way. Party bosses kicked Amash off the House Budget Committee when he decided that the 2012 version of Paul Ryan’s spending blueprint didn’t cut deeply enough (he had voted for the Ryan budget in the past and supported the Republican Study Committee alternative that year).

But at the time Rove made his remark, Amash was the member of Congress who least often voted with Pelosi. He was one of three Republican House members to receive a perfect 100 percent from the Club for Growth and boasts similarly high scores from Heritage Action and the American Conservative Union.

This puts primary challenger Brian Ellis in the awkward position of having to argue simultaneously that Amash is too conservative and not conservative enough. Ellis blasts Amash for not always toeing the party line since the incumbent votes “present” on bills he thinks use unconstitutional means to achieve policy ends he supports. “Then vote for it,” Ellis recently insisted concerning the Keystone pipeline.

But Ellis also hits Amash for voting the party line too much. “Justin was part of the Ted Cruz faction, the threat to default on our debt,” he has told local media. The full House went along with Cruz and Amash until the final vote, including the passage of a continuing resolution that defunded Obamacare.

Whatever you think of Cruz’s strategy and the government shutdown that followed—I had mydoubts—by 2014, that manufactured crisis will be less relevant than the pros and cons of Obamacare itself. If, as appears increasingly likely, the problems continue, Republicans who voted with Cruz might be claiming vindication.

This is why Ellis can only take some of his critiques of Amash so far. “The premise was right,” he said of those trying to defund Obamacare. In the same interview, Ellis conceded the National Security Agency should be reined in, saying, “I agree with what [Amash] is doing.” He was reduced to waving the bloody shirt against Edward Snowden, whom he described as a “flat-out traitor” rather than a whistle-blower for “exposing our precious methods.”

Grassroots conservative groups will be firmly in Amash’s corner. “He’s the gold standard of principled constitutionalism in Congress,” FreedomWorks’s Dean Clancy told The Hill. Some money is still behind him as well, including Amway president Doug DeVos and the chairman of the Chamber of Commerce’s board. The National Federation of Independent Business reportedly won’t endorse against him.

Still, the Amash race is bigger than what Ted Cruz was up to this fall. It has implications for whether the GOP can change course on foreign policy and civil liberties—and whether any forces in the party can meaningfully defy K Street.

W. James Antle III is editor of the Daily Caller News Foundation and author of Devouring Freedom: Can Big Government Ever Be Stopped?

Follow @jimantle