Illegal immigrants, unite! And under the union banner, too.

AT the big pro-illegal-immigration rally on the Mall in Washington on April 10, thousands of demonstrators held aloft dark blue signs that read, "We Are America." Below those words, in smaller letters, was the name "New American Opportunity Campaign," and below that was a web address, www.cirnow.org.

Although not obvious at first glance, the small print on the signs said something important about the aggressive new drive to win acceptance of illegal immigrants. A visit to the website www.cirnow.org--those letters stand for "Comprehensive Immigration Reform Now"--leads to a site for the New American Opportunity Campaign, which in turn leads to a request for donations to an organization called the Coalition for Comprehensive Immigration Reform. "Opportunities should be provided for undocumented immigrants currently living in the U.S. to receive work permits and travel permission and access educational opportunities once they undergo background and security checks," says the groups' platform. "Those who want to settle in the United States should be eligible for permanent residence and citizenship." Both organizations list the same address: 1775 K Street NW, Suite 620, in downtown Washington.

As it happens, that is the Washington headquarters of UNITE HERE, the labor union formed a few years ago by the merger of the Union of Needletrades, Industrial, and Textile Employees, and the Hotel Employees and Restaurant Employees International Union. UNITE HERE--which represents about 460,000 workers in the U.S. and Canada but hopes to unionize millions of newly arrived, low-paid, unskilled immigrant workers--played a major role in organizing the Washington rally, as well as other pro-illegal-immigration events across the country.

Joining UNITE HERE in the immigration fight is the Service Employees International Union (SEIU), which represents about 1.8 million workers in the U.S. and Canada. "You need to legalize the 11 million people who are here on an undocumented status," a top SEIU official told the liberal Air America radio network recently. "Many of them are our members." The chief organizer and spokesman of the Washington rally was a man named Jaime Contreras, who heads the local SEIU chapter and is also in charge of what is called the National Capital Immigration Coalition, a mix of labor, business, church, and civil-rights groups that staged the event.

In fact, SEIU and UNITE HERE, along with a few others like the American Federation of State, County, and Municipal Employees, are key sources of money, talent, and organization in the nationwide campaign to legalize illegal immigrants. "The leadership of organized labor is one of the reasons these marches have been so big," says Mark Krikorian, executive director of the pro-enforcement Center for Immigration Studies, "because there is [a union] infrastructure everywhere to get people mobilized, to rent the buses, to print the signs. All that stuff is important, and that's the advantage that organized labor still has."

The involvement of major unions represents an extraordinary change from just 20 years ago, when labor, embracing the generally accepted proposition that importing millions of low-wage workers would drive down the wages of American workers, still played its traditional role of working to limit illegal immigration and to punish employers for hiring illegal aliens. "Historically, American labor unions have defended the American worker, and immigration has been secondary," says Vernon Briggs, a professor of labor economics at Cornell University. "The labor-union movement was founded mostly by immigrants--Samuel Gompers was an immigrant--but it never confused the immigrant agenda with the interest of American workers."

Why the change? It's all about political power--a labor movement on the decline hoping that a growing immigrant population will help it reclaim the ...