A few weeks ago, I noted in this space that the anti-Tea Party Main Street Partnership is openly appealing to conservative paranoia in a high-profile Idaho race.

The super PAC, run by former Rep. Steve LaTourette, R-Ohio, ran an ad hinting that the challenger to Republican U.S. Rep. Mike Simpson is being backed by a liberal, pro-Nancy Pelosi group from outside Idaho - namely, the uber-conservative Club for Growth.

At the time, I wrote that Main Street might win a couple of races with this dishonest approach – and in fact Simpson will likely win on Tuesday. But to whatever extent this tactic succeeds, it only reinforces the very distrust that has turned primary voters against the “Main Street” model of Republican.

The same thing is now happening in Michigan - except it isn't a super PAC, but actual Republican lawmakers who are launching conservative-sounding attacks against a colleague for holding a principled conservative position.

Rep. Devin Nunes, R-Calif., recently called Rep. Justin Amash, R-Mich., “al Qaeda's best friend in the Congress.” House Intelligence Chairman Mike Rogers, who hails from two districts over, said Amash “votes more with the Democrats than with the Republicans.” Politifact deemed Rogers' assertion to be “false,” finding that Amash “has never voted with his party less than 85 percent of the time in a given year.” (Amash argues that Rogers himself has voted more often with House Democratic Leader Nancy Pelosi, D-Calif., which is true.)

These attacks coincide with a well-funded establishment effort to unseat Amash in the Michigan Republican primary this August – an effort to which Rogers, who is retiring, has contributed $5,000.

Amash is a young libertarian-leaning Republican who won his House seat in the Tea Party wave of 2010. He is one of the most active members of Congress on social media, frequently exchanging tweets with constituents and explaining each vote he takes with a new Facebook update. That's probably necessary, since he frequently finds himself on the unpopular end of bills that pass the House with broad bipartisan support.

At times, Amash's insistence on hewing to abstract principles has put him at odds not only with big business (“I don't think Justin Amash cares if Bank of America gives to him or not,” a lobbyist told Politico last year) but also with more pragmatic conservative goals. He lost the endorsement of Right to Life of Michigan in 2012 because he refused to vote for a bill banning sex-selective abortions. He explained on Facebook that he wants to ban all abortions, but opposes the criminalization of specific motives, for the same reasons he opposes hate-crime legislation.

Amash irritated Republican and Democratic leaders in 2013 by building a bipartisan House coalition to stop privacy abuses by the National Security Agency. He was also among the most outspoken opponents of U.S. involvement in both Libya and Syria.

Hence the hyperbolic charges regarding al Qaeda and Pelosi. Both are framed as coming from Amash's right flank, as if he's gone squishy since coming to Washington - not from a GOP establishment that aspires to build permanent power by trading corporate welfare for contributions from K Street.

The pro-life issue is the one on which Amash's primary challenger, Brian Ellis, is trying to make inroads. And that's smart -- it's a much better issue than, say, southwest Michigan's urgent need for a congressman who will reliably vote to reauthorize the Export-Import Bank and support other corporate welfare programs.

As in the Idaho race, the establishment's anti-establishment message evinces a cynical lack of interest in winning hearts and minds - not even with the pragmatic argument that “our guy can win.” Their best hope is to stoke the very distrust they helped create among conservatives in the first place.

DAVID FREDDOSO, a Washington Examiner columnist, is the former Editorial Page Editor for the Examiner and the New York Times-bestselling author of "Spin Masters: How the Media Ignored the Real News and Helped Re-elect Barack Obama." He has also written two other books, "The Case Against Barack Obama" (2008) and "Gangster Government" (2011).