Judge Roy Moore’s blowout victory in the Alabama Senate race Tuesday deals the most serious in a line of devastating blows to Senate Majority Leader Mitch McConnell’s reputation and authority — as the establishment GOP struggles to put a lid on a brewing civil war from its populist, conservative base.

In his 1945 novel Brideshead Revisited, author Evelyn Waugh describes a main character’s latest crisis as “a blow, expected, repeated, falling upon a bruise, with no smart or shock of surprise, only a dull and sickening pain and the doubt whether another like it could be borne.”

“A dull and sickening pain” is exactly what McConnell and his allies in the GOP establishment and donor class must have felt Tuesday night as they watched their chosen candidate, former D.C. lobbyist Luther Strange, get crushed underfoot by Moore, despite outspending Moore by as much as 10-1.

Although Republicans hold both the Senate and the House, the GOP establishment and McConnell, in particular, have been hammered by a series of defeats in recent months so brutal and so disorientating that they must wonder if another can be withstood.

In addition to the election of President Trump, a man at odds with many of the key platforms of the establishment GOP, the GOP majority in the Senate has been unable to pass anything beyond the most basic legislation; just this week, a second attempt at repealing Obamacare went down in a ball of flames. McConnell was humiliated by the president himself this month when a frustrated Trump went over his head and dealt with Democratic leaders on the debt ceiling.

On Tuesday, McConnell watched as establishment ally and Trump opponent Sen. Bob Corker (R-TN) announced his intention to step down — a move that is likely to see a gritty grassroots challenger face off against whoever McConnell and the donor class select.

Then came Alabama.

Despite pouring tens of millions of dollars into a scorched-earth attempt to destroy the upstart Moore in a desperate attempt to drag the limp Luther Strange over the finish line, by Tuesday night it was clear — Moore had won, and McConnell and his allies had been dealt yet another blow upon an already blackened bruise. That blow is likely to be felt throughout Washington, including in the White House where Senior Adviser Jared Kushner reportedly convinced President Trump to have made the disastrous decision to back Strange.

The establishment is certain to dismiss this as a fluke, a one-off, an upset stirred up by Breitbart News, former White House Chief Strategist and Breitbart Executive Chairman Steve Bannon, for Alaska Gov. Sarah Palin, and other four-letter words. But they already know that it is not. Politico reported ahead of the vote that “mainstream Republicans worry [a Moore win] would instigate a broader offensive by the activist right to unseat other GOP incumbents in the 2018 midterms.”

That movement is already underway, with rumblings that Rep. Marsha Blackburn (R-TN) may run to replace Corker — a primary race that would, no doubt, put the screws on McConnell and could end in a similarly spectacular defeat for the establishment and donor class. Challenges to Sen. Roger Wicker (R-MS), Sen. Dean Heller (R-NV), and Sen. Jeff Flake (R-AZ) could also be forming in light of Strange’s defeat in Alabama.

With the nationalist base fired up after Moore’s victory, McConnell and his fellow elites will likely fall back on their old pitch to voters that their establishment candidates are more “pragmatic” and are able to get things done.

This, therefore, puts intense pressure on them to get something done by year’s end because so far, the pragmatic establishment has only managed to pile legislative defeat on top of legislative defeat. Whenever the establishment has convinced the president to follow their lead, he has faced similar defeat. With Obamacare repeal and replace on life support at best and tax reform looking far from certain, the establishment is in trouble as it pertains to achievements.

The Alabama result should serve to teach McConnell, the donor class, and his establishment allies that betraying your voters and throwing money at the problem will not work. Voters are sending a clear message: “Effect change or we will find someone who will.”

Tuesday night’s result shows that the voters mean it.

Adam Shaw is a Breitbart News politics reporter based in New York. Follow Adam on Twitter: @AdamShawNY.