President Bush's proposal to give legal status to the millions of undocumented workers in the United States would mark the biggest overhaul of U.S. immigration law in nearly 20 years. The issue is re-emerging as an administration priority after having been put on hold in the wake of the September 11 terrorist attacks three years ago.

"This could be one of the most significant changes in U.S. immigration law in half a century because it's going to dramatically increase the number of people allowed into the country," said Steve Camarata of the Center for Immigration Studies, describing the sweeping proposal unveiled by President Bush that would entitle at least eight million people now estimated to be in the United States illegally to obtain legal status.

And, the measures go further than proposals debated in Congress, one of which is co-sponsored by Arizona Senator John McCain, whose state shares a long border with Mexico, source of most of the illegal immigrants now in the United States.

"We have a big problem in America. We have a big problem of hundreds of people dying in the desert. We have a problem. Let's join together and address that problem," said Senator John McCain.

The White House denies this proposal amounts to a blanket amnesty. But according to Hofstra University law professor Peter Spiro, that's more or less what it is. "Although it's not framed as an amnesty, it certainly approaches one. It recognizes that these people are part of the community, that they benefit the community, that they offer labor and other skills that we don't have available," he said.

Only those undocumented aliens who hold jobs in the United States would gain temporary legal status. President Bush says the plan amounts to a common sense policy for an economy where jobs paying minimum wage and in the unskilled service sector are often held by illegal immigrants, jobs that Americans are often unwilling to take.

"If an American employer is offering a job that American citizens are not willing to take, we ought to welcome into our country a person who will fill that job," he explained.

That's the reason why Steve Camarata of the Center for Immigration Studies thinks the proposal is as much about helping business owners as well as illegal aliens. "The business community is very resistant to any effort to reduce the supply of labor because that would mean they would have to pay workers more," he said.

Democratic Congresswoman Nancy Pelosi of California denounced the White House plan as election year window dressing and Arturo Rodriguez, president of the United Farms Workers, expects the measure to face tough opposition in Congress. "What President Bush is talking about right now is all geared toward employers and it does nothing to really protect immigrant workers," he said. "I think there will be a lot of opposition to it because it doesn't go the route that it needs to to really deal with the issues facing immigrants today in this country."

Whether this measure will give President Bush a boost with Latino voters in November's election is far from certain, since those immigrants who worked within the system to become legal may now resent a measure that would allow those who did not to gain the same status.

"One of the main concerns is that an amnesty or a reward for illegal behavior is an enormous slap in the face to people who play by the rules," said Mr. Camarata.

The Bush administration made immigration reform a high priority after taking office three years ago and had worked with the government of Mexican President Vicente Fox to implement a plan. But the September 11 terrorist attacks on the United States had stopped the process in its tracks amid heightened concern over the security of the nation's borders.