US President Donald Trump is ready to sign on to a plan that would open a path to citizenship for as many as 1.8 million "Dreamers," young immigrants brought illegally to the country as children, senior White House officials have said.
The White House presented the offer as a major concession aimed at attracting enough votes from Democrats.
But it includes a number of elements such as tightening border security and deterring new immigrants to appeal to Republican hardliners.
"This is kind of a bottom line for the president," a senior official told reporters, saying it would be up to politicians to determine some of the details.
"If it's realistic, then he'll sign it. If it isn't realistic, then he won't sign it." the official added.
Mr Trump's plan, which the White House hopes will be first voted on in the Senate in early February, would require Congress to set up a $25bn "trust fund" to build a wall on the southern border with Mexico, and invest in better protections at the northern border with Canada.
It would also require Congress to limit family sponsorship of immigrants to spouses and minor children and end a visa lottery system for certain countries, the official said.
Congress would have to allocate additional money to border guards and immigration judges, and change rules to allow for the rapid deportation of illegal immigrants from countries other than Mexico and Canada who arrive at the US border, according to the official.
To become law, the measures would also need to pass the House of Representatives.
A second senior official declined to speculate on whether the plan would pass the Republican-controlled chamber.
"I think the House will have an independent vehicle," the second official said.
"We're not trying to force something on the House." he added.
President Trump, whose hardline immigration stance was a key part of his presidential campaign, said in September he was ending the Deferred Action for Childhood Arrivals, or DACA programme for "Dreamers" that was created by his predecessor Barack Obama, unless Congress came up with a new law.
The DACA protections apply to about 700,000 people, but White House officials estimated there were at least that many illegal immigrants who qualified for the programme but did not sign up for it.
Officials said the 1.8 million people could apply to become citizens in ten to 12 years providing they had jobs and did not commit crimes.
Republican US Senator Tom Cotton, a leading conservative voice on immigration policy, praised President Trump's immigration plan and said he looks forward to working in Congress to turn it into legislation.
"The president's framework is generous and humane, while also being responsible," Senator Cotton said in a statement.
