Tea party challenger David Brat defeated House Majority Leader Eric Cantor (R-Va.) in a shocking primary upset Tuesday night. (NBC 12 Richmond)

In Tennessee, jubilant tea party activists are trading giddy e-mails and laying ambitious plans for a big summer rally. Mississippi organizers are feeling an extra bounce as they prepare for a major get-out-the-vote effort. And an underdog tea-party-backed challenger in Kansas has newfound hope that he might catch a wave and take out the state’s longtime Republican senator, Pat Roberts.

The come-from-behind victory of Dave Brat over House Majority Leader Eric Cantor in Virginia has emboldened conservative activists nationwide, lifting their hopes of scoring more primary wins this year — and gaining renewed sway heading into a wide-open contest for the party’s 2016 presidential nomination.

The invigorated activists face a rapidly closing window to have an impact on the upcoming GOP primaries, with only a few seriously contested races remaining in states such as Michigan and Oklahoma, as well as Kansas, Mississippi and Tennessee. And tea-party challengers could face steeper odds in the coming weeks, as Republican incumbents and business groups are likely to commit more resources in the wake of Cantor’s defeat in hopes of preventing another setback.

‘A wave of energy’

Yet Brat’s victory has infused conservative activists with a burst of energy, coming as the Republican Party, divided over issues such as immigration reform and common education standards, struggles to balance the competing demands of its core factions.

On Wednesday, tea party activists and evangelical leaders, two groups that have been frustrated with the Republican establishment, said they consider Cantor’s defeat a revival of a GOP insurgency with the potential to further erode the power of the party’s traditional leadership.

How David Brat overwhelmed Cantor

“The text messages and e-mails have not stopped flying,” said Ben Cunningham, president of the Nashville Tea Party, which is backing state Rep. Joe Carr’s long-shot challenge to Sen. Lamar Alexander in Tennessee. “It has been an amazing shot in the arm. Dave Brat stated tea party principles simply, articulately, unapologetically, and he got elected doing that. It’s just a great inspiration for everybody.”

The group is ramping up its plans for a major rally next month. “We’re just going to redouble our efforts,” Cunningham said.

Cantor’s loss took even the national tea party groups by surprise. None of them put money behind Brat, who was vastly outspent by Cantor and his outside allies.

But after a year in which the tea party has gained few substantial wins, major groups in the movement jumped to capi­tal­ize on the excitement among supporters.

“It creates a wave of energy that’s just infectious,” said Matt Kibbe, president of the Washington-based tea party group FreedomWorks for America, who sent an e-mail Wednesday to the group’s activists with the subject line, “You’re Winning.”

Business responds

The surge of energy is intensifying the incumbent-protection efforts of the party’s business wing — whose offer to help Cantor was declined — even as it dismissed the notion that Brat was lifted by a wave of organized tea party support.

“The tea party had nothing to do with this,” Tom Donohue, president of the U.S. Chamber of Commerce, told Bloomberg TV on Wednesday. “They weren’t in. They didn’t put any money in. They didn’t have any people there. It was sort of an attractive professor in a very, very conservative district in Virginia. And everybody was surprised.”

Brat’s victory underlined the deep schism in the party between its conservative base and its business wing. In his challenge to Cantor, the economics professor took direct aim at the House majority leader’s relationships with industry groups such as the U.S. Chamber of Commerce and the Business Roundtable.

Speaking to supporters in Mechanicsville, Va., last month, Brat drew applause attacking Wall Street investment bankers who nearly “broke the financial system” and were allied with Cantor.

“These guys should have gone to jail,” he said. “Instead of going to jail, where did they go? They went to Eric Cantor’s Rolodex.”

Mississippi impact

The Chamber of Commerce, which has bolstered GOP candidates in 12 primaries this cycle, is stepping up its efforts in the Senate contest in Mississippi, where Sen. Thad Cochran is locked in a tight race with Chris McDaniel, who forced him into a runoff that will be held June 24. The contest is considered the tea party’s best shot of another big win this cycle.

Strategist Scott Reed, who is helping to develop the Chamber of Commerce’s electoral strategy, said that if McDaniel captures the GOP nomination, it could “jeopardize the Mississippi Senate seat” for Republicans in the general election.

The organization and its allies, which hope to expand the electorate, will be up against energized activists campaigning for McDaniel.

When Brat won Tuesday, “folks here were ecstatic,” McDaniel spokesman Noel Fritsch said. “I think a lot of times folks get a little disillusioned with politics, and this is a clear sign that the system can work and the people’s voice can be heard.”

McDaniel has the backing of radio talk show hosts Laura Ingraham and Mark Levin, both of whom touted Brat’s candidacy when few others were talking about it.

And unlike Brat, he has been lifted by the support of major national groups such as the Club for Growth, the Senate Conservatives Fund and the Tea Party Patriots.

FreedomWorks, which plans to spend $350,000 in a get-out-the-vote operation for McDaniel, will hold a day-long meeting Saturday with grass-roots groups from across the state to begin the effort.

Eyeing other openings

Tea party activists are watching other races in which they think they can make a stand.

In Oklahoma, the race to replace retiring Sen. Tom Coburn is shaping up as another bout between the tea party and the Republican establishment.

And many candidates who have struggled to gain traction are quickly aligning themselves with Brat.

Physician Milton Wolf, a tea party candidate challenging Roberts in Kansas, is trying to link the senator to Cantor.

“Eric Cantor isn’t the only incumbent from Virginia who is going to lose his primary this year,” Wolf said in a statement Tuesday night. “On August 5th, it’s Pat Roberts’ turn.”

Christian conservative activists said they, too, are taking inspiration from Brat’s victory.

David Lane, who is directing a multimillion-dollar effort to mobilize evangelicals, said Tuesday’s results signal trouble for Republican presidential candidates who oppose the party base on key issues.

“This is part of an ongoing battle for the soul of the Republican Party,” he said. He added that prospective candidates such as former Arkansas governor Mike Huckabee and Sen. Ted Cruz (Tex.) “would be in a strong position.”

But top GOP strategists argued that Cantor’s loss was rooted in issues specific to his race and is not a predictor that more Republican incumbents will fall.

“I’ll never say never, but the people who have primaries remaining have been diligently focused on their races for some time,” pollster Whit Ayres said.

As for Cantor, “the seeds of the loss were sown for some time,” he said. “It’s not something that just happened.”

Vin Weber, a former congressman from Minnesota and adviser to Republican Party leaders, said he is disappointed by Cantor’s defeat but is grateful that it occurred so late in the season.

“We are near the end of the primary season, and in most of the primaries, we have nominated solid conservative Republicans who understand that if we are going to be the majority party, we have got to be a governing party,” he said. “Last night produced a different message.”

Jia Lynn Yang and Sean Sullivan contributed to this report.