Immigration activists had been following Eric Cantor’s race closely. He seemed to be their last hope in passing any kind of immigration reform in the House.

But Cantor’s loss on Tuesday has upended the whole immigration reform movement, with advocates on both sides of the political aisle questioning the measure’s future. Cantor, a Virginia Republican, was defeated by a little-known Tea Party-back candidate, Dave Brat, in the primary race which featured immigration as the central issue.

[Immigration] is really dead now.

- Roy Beck, president of Numbers USA, which opposes immigration reform

The stunning loss, many say, almost certainly ended whatever slim hopes remained for a deal on immigration in the House this year, likely putting the issue on ice until after the 2016 presidential election.

"It's really dead now," said Roy Beck, president of Numbers USA, a group that opposes comprehensive immigration legislation. Immigration "has been pronounced dead many times over the last two years, but I think the voters of Cantor's district have sent an incredible message."

Brat accused Cantor of embracing "amnesty" and open borders, signed an anti-immigration pledge, and got assists in recent weeks from conservative figures popular with tea party voters such as radio host Laura Ingraham and columnist Ann Coulter, who labeled Cantor "amnesty-addled."

Cantor fought back, boasting in strongly worded mailers of shutting down plans to grant "amnesty" to "illegal aliens" — a changed tone for a lawmaker who'd spoken out in favor of citizenship for immigrants brought illegally to this country as youths.

He hardened his stance on the policy, moving to block House action last month on a GOP-authored measure offering citizenship to certain immigrants here illegally who serve in the military.

It wasn't enough.

After a primary election season in which immigration had barely registered, the outcome suggested that it can still be a potent political issue for Republican primary voters.

Some immigration advocates and pollsters cautioned it was too soon to say whether immigration was the deciding factor for Cantor. David Winston, a GOP pollster who advises House Republicans, said that had Cantor known he was truly threatened, he would have campaigned differently, possibly producing a different outcome. Instead, Cantor's internal polling had shown him comfortably ahead.

"Was that the key issue? We don't know because the candidate never thought he was in a race," Winston said.

Immigration advocates also noted that some GOP candidates who embraced immigration legislation escaped their primaries unscathed. Sen. Lindsey Graham, R-S.C., an author of the comprehensive immigration bill that passed the Senate last year, won his primary handily Tuesday.

Another House member, Rep. Renee Ellmers, R-N.C., also won last month even though her opponent attacked her as a supporter of relaxing immigration laws.

Some Democrats were still holding out hope for action. "Now Mr. Cantor can do the right thing instead of the political thing," said Rep. Joe Garcia, D-Fla.

But Cantor's loss was such a stunning rebuke for a politician seen as next in line to be speaker of the House that it immediately emboldened conservative opponents of immigration legislation.

For a Republican House rank and file already reluctant to take on the politically volatile issue in an election year, the outcome offered an object lesson on the benefits of steering clear.

And for establishment Republicans who've been pushing support for an immigration overhaul as the best way for the GOP to win back the Latino voters crucial to national elections, Tuesday's result was a sobering setback. In the year since the Senate passed a comprehensive immigration bill, House Republicans have resisted the entreaties of the business community, religious leaders and the GOP establishment.

That doesn't look likely to change anytime soon.

"We're all shocked that you got the No. 2 Republican taken down and the entire campaign was on immigration," said Hector Barajas, a Republican consultant in California who is trying to sell the GOP to Hispanics. "That emboldens the Ted Cruzes of the world to go out there and say 'I told you so.'"

Based on reporting by The Associated Press.

Follow us on twitter.com/foxnewslatino
Like us at facebook.com/foxnewslatino