Organized labor has become a leading proponent of President Barack Obama’s immigration agenda, a departure from more than a century of hostility to foreign-born workers.

Some of the nation’s most influential labor leaders have heaped praise on comprehensive immigration plans that will help grant citizenship to many of the nation’s 11 million illegal immigrants.

The AFL-CIO, one of the nation’s largest labor unions, kicked off a 14-city rally backing the president’s plan on Wednesday.

“This is a top priority for America’s unions because a roadmap to citizenship for those who are American in every way except on paper is critical for all working people” AFL-CIO President Richard Trumka said in a statement. “We understand that solidarity means standing together with predominantly immigrant workforces to improve wages and workplace safety.”

Some labor and immigration experts say Big Labor’s enthusiasm for legalization efforts stems from solidifying political support for the Democratic Party, as well as declining union membership.

“Organized labor is a wing of the Democratic Party now, even tighter than it was in the past, and Democrats are heavily invested in open immigration,” said Vincent Cannato, professor at University of Massachusetts Boston. “Organized labor is hoping that this creates a strong Democratic Party, which will play into their own interests.”

The vast majority of illegal immigrants who would be amnestied are Hispanic; Obama won between 70 and 75 percent of Hispanic voters according to 2012 exit polls. That voting bloc is even more reliably Democratic than unions; AFL-CIO exit polls showed that 65 percent of union members cast ballots for the president’s reelection.

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