By nearly all accounts, they should have had their victory. Conventional wisdom had left Sen. Thad Cochran for dead after a close June 3 primary sent him into Tuesday’s runoff against former conservative radio host Chris McDaniel. The challenger was supposed to have an easy lift after winning more votes than Cochran in Round 1. House Majority Leader Eric Cantor’s surprise defeat by conservative upstart Dave Brat days later only reinforced that perception.

But Cochran, unbowed, expanded the electorate, bringing in Democratic voters and defeating McDaniel to almost certainly secure a seventh term in office. The results left establishment Republicans celebrating, having also beaten back Tea Party challengers in Oklahoma and upstate New York. As McDaniel refused to concede in a fiery speech decrying that “the conservative movement took a backseat to liberal Democrats in the state of Mississippi,” conservatives and Tea Party activists were left wondering where they went wrong—and seething at their defeat. The results show the success of a sweeping tide of establishment push-back following high profile upsets in Republican primaries in 2010 and 2012.

The Mississippi race pitted the National Republican Senatorial Committee, former Mississippi Gov. Haley Barbour’s political machine, and outside groups like the Chamber of Commerce and American Crossroads against a conservative barrage from the Club for Growth and Tea Party organizations. The NRSC, Senate Republicans’ campaign arm, spent roughly $500,000 on get-out-the-vote operations for the runoff alone, with 45 NRSC staff and volunteers knocking on 50,000 doors from the initial primary until the runoff, an official said.

“If Republicans are going to act like Democrats, then what’s the use in getting all gung-ho about getting Republicans in there,” Sarah Palin said on Fox News late Tuesday.

Amy Kremer, the former chair of the Tea Party Express, wrote on Twitter that the “GOP is done.”

“What just went down in Mississippi, with the GOP establishment despicably playing the race card against its own base in the U.S. Senate run-off, is a point of no return moment for conservatives in the party,” influential Iowa conservative radio host Steve Deace said in a Facebook post, referring to Cochran’s courtship of black Democrats. “This is a Hemlock Society victory, with the GOP establishment essentially signing its own suicide pact. It’s unforgivable, really, and it should be. I’m going to make everyone that comes to Iowa running for president and wants my support go on the record about this. It’s a line in the sand moment. You cannot align yourself with people who treat you this way. Anybody that thinks otherwise is never going to fight the system if we elect them. These tactics in perhaps the most conservative state in the union are heinous and ought to be condemned without equivocation. If a candidate isn’t going to condemn these sorts of tactics used against us, they will not stand up for us once elected.”

And conservative activist Daniel Horowitz called Cochran’s pursuit of Democratic votes in a Republican primary “treachery.”

“Campaigning openly for Democrat votes in a GOP primary using issues and arguments contrary to the party platform is one thing,” Horowitz wrote on Breitbart. “But the fact that they played the race card and ran mailers and robo calls in African American areas accusing their own party of being racist is downright despicable.

“How much longer can a party survive when its leadership is inexorably against the ethos of its base?” Horowitz added.

In a statement Wednesday morning, Club for Growth President Chris Chocola put the defeat in the context of the group’s 10-year struggle to bring the GOP closer to conservative principles. “We are proud of the effort we made in Mississippi’s Senate race and we congratulate the winner,” he said. “We expect that Senator Cochran and others gained a new appreciation of voter frustration about the threats to economic freedom and national solvency. In light of our experience of the last ten years, we move forward even more confidently than we did the day after the 2004 Pennsylvania primary.”

Conservative political consultant Keith Appell cautioned against interpreting Tuesday’s results as a knockout punch against the Tea Party, blaming McDaniel’s failure to win the required 50% of the vote in the initial primary on a blogger who incited outrage—and sympathy for the incumbent—by strangely filming inside the nursing home housing Cochran’s ailing wife.

“Interpreting this as some kind of ‘Empire Strikes Back’ moment is an overreach,” Appell told TIME. “It’s a golden opportunity blown, to be sure, but it underscores how even a good candidate isn’t enough—he or she still has to have a competent campaign. Republican leaders and their establishment backers dodged a bullet but there is still a deep and active discontent among the grassroots and it will only continue to manifest until the leadership reconnects with its base.

“Conservatives and Tea Party activists have to take the long view, the big picture is that they’re really winning,” Appell added.

RedState founder Erick Erickson wrote that he does not back the third-party approach advocated by some. “I’m just not sure what the Republican Party really stands for any more other than telling Obama no and telling our own corporate interests yes,” he said.

“As grassroots activists feel further and further removed and alienated from the party, it will become harder and harder to win,” Erickson added. “The slaughter the GOP will inflict on the Democrats in November will be a bandaid of built in momentum. When the GOP inevitably caves on repealing Obamacare, opting instead to reform it in favor of their donors’ interests, we may just see an irreparable split. Then, and even worse, if party leaders and party base voters cannot reconcile themselves to a common candidate in 2016, God help us.”

Correction: The original version of this story misstated how many terms Thad Cochran has been in the Senate.

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