Backers of overhauling immigration rules began a congressional push Wednesday to give temporary legal status to up to 1.5 million illegal immigrant workers to provide a labor pool for U.S. agriculture.

The proposal is a recycled version of parts of a bill that stalled after passing the Senate last year. Republicans in the House of Representatives blocked negotiations on the measure, sticking with a get-tough stand against illegal immigrants before the November elections.

Those wanting to liberalize immigration laws hope the combination of a Democratic majority in Congress, support from President George W. Bush and a perceived backlash against anti-immigration rhetoric in the elections will help power the comprehensive immigration proposals.

"The reality is Americans have come to rely on an undocumented migrant work force to harvest our crops," Sen. Diane Feinstein, a Democrat, said at a news conference.

Under the bill, illegal immigrants who can show they have labored in agriculture for at least 150 work days for the past two years would become eligible for a "blue card" bestowing temporary legal status. Their spouses and minor children also could get a blue card if they already live in the U.S.

People with these cards who work an additional three years, at least 150 days a year, or five years, at least 100 days a year, would be eligible for legal residency. But they first would have to pay a $500, be up to date on taxes, have no record of committing crimes involving bodily injury or threat of serious bodily injury or have caused property damage of more than $500.

The blue card program would end after five years, unless it is renewed. The bill would reduce the time it takes to get a visa for an immigrant who wants to come to the U.S. to work in agriculture.

Among those supporting the bill are Sen. Edward M. Kennedy, a senior Democrat and a chief architect of last year's Senate immigration bill, and Sens. Larry Craig and Mel Martinez, both Republicans.

Opponents say immigrants provide cheap, exploitable labor to the industry and deflate wages for American employers. They also contend such workers become a drain on taxpayers because those workers, once eligible, turn to welfare, medical plans and other social programs.

But proponents are getting support from growers who saw their crops left to waste in fields because of farm worker shortages last year.