Reporting from Washington — With their prospects in Congress sinking along with the economy, liberal advocates of giving undocumented immigrants a path to citizenship are launching a risky strategy to push lawmakers and the White House to take up their cause.

They are devising a proposal in which millions of undocumented workers would be legalized now, while the number of foreign workers allowed to enter the country would be examined by a new independent commission, and probably reduced.

It is a calculation designed to win a new and powerful ally, organized labor, which favors a limit on foreign worker visas. But it risks alienating businesses that rely on temporary workers and could turn off key Republicans such as Sen. John McCain of Arizona, who in the past has crafted his own compromise plan for legalization.

With unemployment on the rise, the immigration debate has moved to the back burner as lawmakers fear enacting a law that could be portrayed as beneficial for immigrants at the expense of struggling American workers.

Advocates believe that winning support from the AFL-CIO, which opposed previous legalization plans, will help get the issue back on track.

"Last time the coalition was not quite as solid as we would have hoped," said Ali Noorani, director of the National Immigration Forum, one of the advocacy groups negotiating with labor leaders over the new strategy.

Ana Avendaño, the AFL-CIO's point person on the issue, said the labor federation believes the Democrats' enhanced power in Washington represents a "sea change" in which liberal groups can forge ahead without working with Republican-leaning business lobbyists.

"The reality is that we no longer have corporations controlling public policy in the White House and on the Hill," she said.

President Obama reiterated his support for legalization last week during a stop in Southern California, and he told members of the Congressional Hispanic Caucus that he would deliver a public statement of support this spring. But advocates are growing anxious that he might prefer to delay what would no doubt be a politically charged fight. Immigration advocates have already raised concerns that the administration has not called off workplace raids that are splitting immigrant families.

Rep. Luis V. Gutierrez (D-Ill.) said he and other caucus members leaned on the president to act fast, pointing out that he had found time to satisfy other constituencies.

"We're saying, 'OK, you took time out for stem cell research, and you're taking time out for healthcare,' " Gutierrez said. "And our communities expect you to take time out for our issues."

To bolster their cause, advocates are planning an $18-million media and grass-roots campaign for the fall. The funding is coming primarily from liberal foundations, including one founded by billionaire activist George Soros.