The establishment strikes back. Well, the Utah establishment anyway.

One word, my friends: RINOlution.

As a result, Lee’s approval ratings in Utah have cratered, and prominent Republicans and local business executives are openly discussing the possibility of mounting a primary challenge against him. Top Republicans are also maneuvering to redesign the party’s nomination system in a way that would likely make it more difficult for Lee to win reelection in 2016…

Spencer Zwick, a Utah native and national finance chairman for Mitt Romney’s 2012 presidential campaign, was more direct, calling Lee a “show horse” who “just wants to be a spectacle.”

“Business leaders that I talk to, many of whom supported him, would never support his reelection and in fact will work against him, myself included,” Zwick said…

“You don’t have ideological wack-jobs,” [former Utah Gov. Jon] Huntsman said. “For all of its labeling as a red state, underneath it all Utah is a pretty pragmatic Western state, a just-get-it-done ethos.”

There’s a lot going on here. One: Whatever you think of Lee’s “defund” strategy, he’s not just a “show horse.” Last month he introduced a credible tax reform plan to help the middle class that was widely well received by conservative wonks. One of the misfortunes of “defund” is that it sucked away some deserved attention Lee might have gotten for that proposal. Two: Not all of this is local Utah politics. As Erika noted the other day, business interests nationally are quietly organizing to target populist Republicans who were willing to risk an economic hit from a shutdown in the name of waging a broader ideological battle. John McCain, in fact, admitted that it was business groups that have been urging him to run again in 2016, knowing that he’ll be a bulwark against the populists in the Senate. Utah is one front in a wider war. Three: Some of this is local Utah politics. It was Bob Bennett, remember, who was ousted in the first big grassroots tea-party coup against longtime GOP incumbents in 2010. Mike Lee is the guy who replaced him. Establishment figures in Utah, whether out of disdain for Lee’s style, friendship with Bennett, or pique at having lost their pipeline to influence in Congress might be looking for revenge. Knocking off the man who knocked off Bennett and replacing him with someone more centrist would be a huge symbolic victory for the establishment both in Utah and nationally.

But how will they do it? Aha:

Even before the shutdown brought Mr. Lee to national prominence, some Utah party and business leaders had begun a $1 million petition drive to overturn the state’s caucus system that brought him to power. That system, which gives grass roots delegates a large say in picking party nominees, toppled incumbent GOP Sen. Robert Bennett —a more conventional conservative—in 2010 amid a wave of anger over passage of the health-care law. Mr. Lee went on to win the seat that November…

Republican circles are now rife with talk of who might challenge Mr. Lee in 2016. So far, no one is firmly raising a hand. But the Count My Vote initiative to do away with the state’s caucus system, backed by many of the state’s largest GOP donors and business names, represents perhaps the best-organized effort in the country to counteract the tea-party wave in the 2010 elections.

Mr. Lee could face a tougher route to re-election in 2016 if GOP caucuses are replaced with a direct primary. That would allow a more centrist candidate to make an appeal to all Republican voters, not just the activists who dominate caucuses, political observers say.

It’s hard to beat a tea partier at a GOP caucus/convention. Passionate grassroots righties will turn out in force while squishy centrists won’t and there’s little that money can do to change that. Replace the convention with a statewide primary, though, and then you can carpet-bomb Lee, who’s not a prolific fundraiser, with ads. His support has taken a hit with voters there: A BYU poll conducted during the shutdown put his favorable rating at just 40 percent, which doesn’t tell you much about where it’ll be come 2016 but feels weak enough to have several potential big-name challengers buzzing. One, per WaPo, is the former chair of the state GOP, who admits openly that he’s considering running because he’s “exasperated” with Lee; another is Dan Liljenquist, who tried to unseat Orrin Hatch last year in the primary and who published an op-ed two weeks ago criticizing Lee for having damaged his effectiveness in the Senate. Huntsman would be another obvious possibility, although grassroots conservatives’ contempt for him as a supreme “No Labels” RINO might galvanize more tea-party support for Lee than a lower-profile challenger would. Per the Journal, some people are even batting around the idea of backing one of Mitt Romney’s sons to unseat Lee. Dave Weigel notes that Romney ran far better in 2012 in Utah than Lee did in the big Republican year of 2010, so the Romney brand is a real asset.

Key question: Will national establishment Republican groups get involved or will a primary against one of the heroes of “defund” be too hot for them to risk in 2016? They’ll be sorely tempted to jump in — not because they have any special animosity for Lee, who’s way more low-key in his criticisms of them than a loud-and-proud flamboyant populist like Ted Cruz is, but because at a minimum they might be able to suck tea-party money into Utah to protect that seat and away from primary challenges to GOP incumbents in other states. If they can force TPers to fight there, they’ll take that — putting the grassroots on the defensive means they’re less of a threat to go on offense elsewhere. If they can’t force TPers to fight there, they’ll take that too — that’ll leave Lee in real jeopardy of being primaried, which, like I said above, would be a big symbolic victory for RINOs everywhere. Then again, at the rate we’re going, the GOP and the tea party will be two fully separate entities by 2016, so maybe this is all academic.