Richard Trumka, AFL-CIO president, speaks to reporters with other labor leaders at the White House on Feb. 5, 2013, after a meeting on immigration reform. (Brendan Smialowski/AFP/Getty Images)

AFL-CIO President Richard L. Trumka, a major backer of President Obama’s immigration push, said in an interview Wednesday that a border plan being developed by House Republicans was a “nonstarter” because it would stop short of offering citizenship to the nation’s 11 million undocumented immigrants.

The head of the nation’s largest labor union said that the emerging House GOP proposal, which would offer immigrants limited legal status, was “fool’s gold” that would be strongly opposed by labor and other key interest groups on the left.

Union opposition would present a serious obstacle to an immigration deal in the House, where many conservative Republicans also oppose an agreement from the other side of the political spectrum.

News that Speaker John A. Boehner (R-Ohio) could offer immigrants legal status in a list of immigration principles at a House GOP retreat this week has given the Obama administration and many immigration advocates hope that a landmark deal could be reached this year. The last major overhaul of border laws was in 1986.

But Trumka was emphatic that, if a “direct” path to citizenship is not included, the AFL-CIO would withdraw from a broad coalition that helped the White House shepherd a comprehensive overhaul of immigration laws through the Senate last year.

The state of U.S. immigration See how immigration trends have shifted over the years.

“It means they would never get citizenship, never get a green card,” Trumka said during an hour-long interview in his office overlooking the White House. “It’s a joke. It’s a hoax, is what it is. It’s like fool’s gold.”

Trumka’s concerns underscore the challenge for Obama and congressional Democrats as they begin to assess the merits of a House Republican proposal. While Boehner navigates his own treacherous terrain to put forward a plan that could win enough support from House conservatives, Democrats could face an uprising from the left if they make concessions on their long-stated demand that any bill include a “special path” to citizenship for the undocumented population.

The Senate approved a bipartisan plan in June that featured a 13-year path for most undocumented immigrants. But the White House and other immigration advocates said it is too early to pass judgment on the House proposals until more details are presented.

For example, advocates said, a House plan to grant immigrants legal status and allow them to pursue citizenship through existing channels could potentially lead to compromise if Republicans also agreed to streamline the process to eliminate backlogs of green-card applicants that could take more than two decades to process.

“I could take those [GOP] concepts and develop them in a way that met our standards . . . and there’s also a way of detailing them in a way very few legal immigrants would have a shot at citizenship,” said Frank Sharry, executive director of America’s Voice, a leading immigration advocacy group. “It’s hard to negotiate with principles, and we’re not going to negotiate with ourselves. Let’s wait and see what they come up with and whether they are within shouting distance of what we want.”

The AFL-CIO — whose opposition to an immigration overhaul in 2007 over concerns about new visas for low-skilled workers helped scuttle that deal — has vigorously supported Obama’s effort. The organization invested $1 million in television advertisements last fall targeting Republicans in five cities over immigration.

Trumka said he is adamant because employers take advantage of noncitizens to drive down wages and benefits in ways that hurt American workers. He said some employers use the threat of deportation to force noncitizens to accept abusive conditions, citing the case of a union member who was recently deported after filing a claim over nonpayment of his salary.

“Without citizenship, it’s a nonstarter because you can’t fix a broken immigration system and create a vast class of millions of people living in the community and working in our workplaces without citizenship. You can’t do that. They have no rights,” Trumka said. “The labor unions are united. Our price of admission is citizenship. Republicans aren’t talking seriously until they start talking about citizenship, and that means a direct route to green cards and a real path to citizenship.”

Trumka’s remarks came a day after Obama renewed his call for immigration reform during his State of the Union address Tuesday night, though he devoted just 120 words to the topic in an hour-long speech. Obama did not mention a path to citizenship — which he explicitly called for in his 2013 speech — and instead cast immigration reform as a boon to the economy in an apparent signal to conservatives.

White House aides said Obama’s intent was to give House Republican leaders “space” to craft their proposals without the president potentially driving away supporters.

But Obama faces mounting pressure from immigration advocates to halt a record number of deportations during his tenure, which is set to top 2 million this spring — more than the George W. Bush administration removed from the country in eight years.

That pressure is why some advocates believe the White House and congressional Democrats would potentially accept a compromise on citizenship with House Republicans. Recent polls show that a majority of Latino immigrants believe ending deportations is more important than gaining citizenship.

“It’s a situation where a lot of it is how it’s framed,” Kevin Appleby, director of migration policy for the U.S. Conference of Catholic Bishops, said of the potential GOP proposals. “If people get legal status and have an opportunity to become citizens, then they’re not necessarily a permanent underclass. If Republicans say legal status and bar them from ever becoming citizens, that’s a permanent underclass.”