WASHINGTON – Leaders of top labor groups on Monday denounced the Republican immigration agenda as detrimental to American workers, citing a new report by the pro-immigration America's Voice that says the legalization of undocumented immigrants would be a boon to the US working class.

On a conference call with reporters, labor leaders from the AFL-CIO and SEIU joined forces with pro-immigration groups to argue that the "anti-worker" stance of key Republicans on the judiciary committee would put US labor at a disadvantage by offering amoral employers the opportunity to hire undocumented workers without legal rights, who they can exploit with low wages and poor conditions.

"Offering citizenship is going to bring them out of the shadows," said AFL-CIO executive vice president Arlene Holt-Baker, in response to a question from Raw Story. "Then the unscrupulous employers would no longer be able to discriminate against them in the way that they do -- paying them unfair wages, making them contract workers when they are not, stealing their wages."

"We're a nation of immigrants," added Eliseo Medina, a spokesman for SEIU. "These are not the first immigrants ever to come to our shores. From the earliest days in the history of this country, people have been coming here, they've been contributing and they've been integrated into our society."

Republicans, who now control the House of Representatives, have stressed border security and stauncher enforcement as part of their immigration agenda, ardently opposing proposals by Democrats to legalize the population of undocumented workers.

They have argued that offering citizenship to the millions of workers who entered the US illegally would be an affront to American workers and create more hurdles for them to get jobs by saturating the labor market.

Holt-Baker invoked a report by the Center For American Progress last year that said granting legal status to undocumented immigrants would lift wages for US workers across the board.

The alliance between the labor and immigration groups reflects a common purpose borne by new realities -- for most of their history, labor unions opposed loosening immigration restrictions. America's Voice executive director Frank Sharry said the coalition would pressure the new Republican majority to alter its position in the issue.

Congressional support is presently lacking for comprehensive immigration reform, with Republicans virtually unanimously opposed and some Democrats reticent to back their leaders' proposals. The immigration and labor leaders said they didn't expect President Barack Obama to stress the issue in his State of the Union address Tuesday.

The report by America's Voice, which sponsored the call, concluded that "the House Republicans' immigration plan would only make a bad situation worse by spending billions more taxpayer dollars on deportation, pushing millions more workers into the underground economy, and continuing the status quo where unscrupulous employers hold a powerful advantage over their law-abiding competitors and a captive workforce."