House Majority Leader Eric Cantor was defeated in a Republican primary Tuesday, conceding his Virginia seat to a local activist after a stunning loss with possibly dramatic consequences for leadership, the chances of any immigration overhaul passing Congress and the future of his party.

He is the first majority leader ever to fall in primary defeat — the position was created in 1899.

Cantor, toppled by college economics professor Dave Brat, 56 percent to 44 percent, conceded just after The Associated Press declared the race over.

Democratic and Republican leadership aides expressed total disbelief and dumbfoundedness Tuesday night. Political operatives in the Old Dominion and organizers in Washington quickly studied election law to see if he could run as a write-in.

With his wife, Diana Fine Cantor, at his side, Cantor choked back emotion and did not sound like a man aiming to stage a comeback.

“I know there’s a lot of long faces here tonight. It’s disappointing sure, but I believe in this country, I believe there’s opportunity around the next corner for all of us,” he said.

Cantor has been a contentious figure within the GOP, never more so than early in the speakership of John A. Boehner, when speculation abounded about his background attempts to overthrow the Ohio Republican.

But that talk had been tamped down in recent years and the two leaders worked in tandem. In many ways, Cantor had been the intellectual leader of the House Republicans, preferring a hands-on approach to Boehner’s famously laissez-faire demeanor.

Cantor is known inside the conference as the leader most interested in projecting a kinder, gentler, approach for the party, not only on immigration but also at the margins of social policy.

The majority leader reflected that in his concession speech, in which he talked about his interest in helping society’s most vulnerable.

Cantor rose to prominence along with Kevin McCarthy of California and Paul D. Ryan of Wisconsin, as the triumvirate of “Young Guns” who would engineer the most recent conservative revolution. They recruited the very style of candidates who have been rattling establishment figures since the tea party wave began in 2010, making the defeat all the more astonishing because it came at the very hand of the movement he helped create.

He also is viewed as someone willing to confront President Barack Obama at every turn, a strategy that defined the House GOP from almost the moment Obama took office. Cantor took the lead early in 2009 to offer suggestions for the economic stimulus package, but was flatly rejected by the president, who bluntly told Republicans he planned to ignore them because elections have consequences.

During his concession speech, Cantor lauded his own efforts on charter schools and a medical research act named for a girl in his district who died last year.

He said it had been the pleasure of his life to be majority leader.

“We need to focus our efforts as conservatives, as Republicans, on putting forth our conservative solutions so that they can help solve the problems for so many working middle-class families that may not have the opportunity that we have,” he said. “We can also put our solutions to work for the most vulnerable.”

Earlier in the day, Cantor took part in a news conference touting legislation to address the Veterans Affairs scandal, not letting on any sign of worry about the impending loss.

Neither Cantor nor his aides seemed have any idea he was in political danger throughout the day Tuesday. GOP aides reached by phone were stunned by the news of Cantor’s defeat, likening it to the surprise resignation of then-Speaker Newt Gingrich, R-Ga., in 1998, followed shortly by the perhaps even more surprising resignation of his would-be successor, then-Rep. Bob Livingston, R-La., after admitting to an affair.

In 2004, Senate Minority Leader Tom Daschle lost his South Dakota Senate seat. The only recent upset in a nomination fight that’s remotely analogous was in 2010, when Robert F. Bennett, then No. 5 in the Senate Republican leadership, was kicked off the general election ballot in Utah thanks to the early tea party insurgency of Mike Lee.

Before that, the most prominent member to be denied renomination was in 1972, when House Judiciary Chairman Emanuel Celler lost his primary bid for a 26th term in New York to Elizabeth Holtzman. He was the longest serving member who’s ever been defeated.

Much of the current conference’s policy direction, from the emphasis on cutting Supplemental Nutrition Assistance Program funds to later attempts to add money to pediatric research coffers, had come directly from Cantor’s office. Over the past year, Cantor had attempted to transition that influence to a legislative re-branding of the Republican Party, emphasizing policy that could attract voting constituencies generally unlikely to vote GOP. But he was met with resistance from his rank-and-file members at almost every turn, and was unable to transition the message into reality.

Rep. Tim Huelskamp, a Kansas Republican not shy about criticizing leadership, told CQ Roll Call the results prove the existence of a strengthened conservative movement. “Eric Cantor is gone because the tea party is not dead,” he said.

Huelskamp also said the Brat victory “weakens” Boehner and predicted others would step forward right away.

No doubt the leadership structure, including Boehner’s security as speaker and Cantor’s deputies inside the party, is now very much in question. Ambitious Republicans eager to reshape the conference will see this as an opening, and possibly an indicator of where policy should be directed.

There were differing takes on the future of any immigration overhaul.

Most took it as a warning sign for immigration advocates, given that was a focus of Brat’s campaign.

“Eric Cantor has been the No. 1 cheerleader in Congress for amnesty,” Brat told half a dozen reporters on May 28, adding that “no Republican in this country is more liberal on immigration.”

The White House and immigration advocates such as Frank Sharry of America’s Voice said the opposite, calling Cantor an immovable obstacle to any legislation moving forward.

A knowledgeable Republican consultant in Virginia told CQ Roll Call that no one saw this coming.

“The worst case scenario that they were contemplating was, ‘OK this is the end of the campaign for speaker.’ None of them contemplated a loss,” the consultant said. “They were pleased with their level of turnout they were seeing throughout the course of the day, because the models that they had indicated a higher turnout was going to be better for them. They completely missed it.”

Virginia Democrats, many who were gathered to celebrate the life of the late longtime campaign strategist Mame Reiley just hours before polls closed, were shocked and unprepared for the loss. They found it a cause for celebration.

Democratic Congressional Campaign Committee Chairman Steve Israel of New York boasted in a statement that the defeat will force the GOP to run “further to the far right with the Tea Party striking fear into the heart of every Republican on the ballot and cementing the dysfunction that has paralyzed this Congress and prevented them from taking any action to help middle class families.” He did not mention the 7th District candidate Jack Trammell, a professor at the same school where Brat heads the Economics department.

In a statement two hours after Cantor conceded, House Minority Leader Nancy Pelosi declared the next five months an open season: “As far as the midterms elections are concerned, it’s a whole new ballgame.”

Jay Hunter, Kyle Trygstad, Emma Dumain, Emily Cahn, Alexis Levinson, Shira T. Center and Jason Dick contributed to this report.

Related stories:

Eric Cantor Loses Primary in Massive Upset (Video)

Republican Senate Primary Challengers Jump on Eric Cantor Loss

Boehner Statement on Cantor’s Defeat

Eric Cantor’s Defeat Was in the Immigration Tea Leaves

On Immigration, the Pressure Mounts for Eric Cantor

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Cantor’s Pediatric Research Bill Could Have Been a Bust

Eric Cantor: A Brief Biography

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