Arizona is poised to introduce America's toughest laws against illegal aliens in a move that is focusing renewed attention on the country's dysfunctional immigration system.
The border state, which has an estimated 460,000 illegal immigrants, plans to give police the power to stop and detain people who do not have legal papers.
It will also ban ''illegals'' from congregating on street corners to look for day labouring jobs, while making it an offence to employ or transport them.
A committee of the state legislature will start examining the proposals today. They have already passed the Senate and must be reconciled with a bill in the House.
Observers expect the proposals to become law within weeks, adding pressure on President Barack Obama who pledged to fix haphazard immigration rules in his first year in office.
Several thousand people descended on Washington last week, calling on the President to make good his pledge to give legal status to millions of illegal immigrants and create a more orderly migration system.
An estimated 12 million illegal immigrants live in the US, many of whom work menial jobs. However, resentment has intensified as employment opportunities have shrunk during the recession.
Civil libertarians have labelled the proposals, which essentially make undocumented entry into the state a criminal trespass offence, as unconstitutional and inhumane. They say the laws could encourage racial profiling.
But Russell Pearce, the senator who sponsored the crackdown, countered: ''When you come to America, you must have a permission slip, period. You can't break into my country, just like you can't break into my house.''
He said the bill would give police a weapon against lax federal enforcement of immigration laws. ''It will be, there's no doubt, the toughest immigration enforcement bill in the nation,'' he said.
Immigration advocacy groups have lobbied hard against the bill. ''The really dangerous impact is the creation of a new state crime related to trespassing,'' Jennifer Allen, director of the Border Action Network, told the ABC network. ''If law enforcement has a reasonable suspicion that someone is undocumented, they can be stopped and forced to prove they are a US citizen. If they can't prove it, they can be arrested.''
The legislation has the support of the Republican Governor, Jan Brewer, which is adding to the discomfort of John McCain, the party's 2008 presidential candidate and a long-standing Arizona senator.
Facing one of the toughest primary challenges in his 27-year career, Senator McCain previously supported a bipartisan push for an amnesty for illegal immigrants. He has declined to comment on the proposals.
But challenger J. D. Hayworth, a former Republican congressman, supports the bill and has attacked Senator McCain's silence.
He told a weekend rally: ''It is unconscionable that nearly a decade after 9/11, the back door of the United States remains open. Our senior senator is looking at this entirely the wrong way.''