President Trump is proposing a path to citizenship for an estimated 1.8 million young undocumented immigrants in exchange for hard-line steps to increase border security and curb legal immigration, a trade-off swiftly opposed by key Democrats.

Trump's support for "dreamers" who have been in the country illegally since they were children represents a significant concession to Democrats and was intended as a compromise to help break the impasse over immigration in Congress, White House aides said Thursday.

The plan offers a citizenship path to more than twice as many dreamers as were enrolled in a deferred action program Trump terminated in September, a move that is likely to engender fierce blowback among some conservatives, especially in the House.

But in a sign of how fraught the prospects for an immigration deal remain, the proposal was met with disdain from House Minority Leader Nancy Pelosi (D-Calif.), as well as members of the Congressional Hispanic Caucus.

In addition to the citizenship path that would take up to 12 years, the White House framework includes a $25 billion "trust fund" for a border wall and additional security upgrades on the southwestern and northern U.S. borders. And the president is proposing terminating the ability of U.S. citizens to petition for permanent legal residency "green cards" for parents and siblings, limiting the family visas to spouses and minor children.

Drew Hammill, a spokesman for Pelosi, called the deal a "ransom" in pursuit of an "anti-immigrant wish list."

Rep. Luis V. Gutiérrez (D-Ill.), one of the most outspoken immigrant advocates on Capitol Hill, said the plan "doesn't pass the laugh test."

"It would be far cheaper to erect a 50-foot concrete statue of a middle finger and point it towards Latin America," he said, "because both a wall and the statue would be equally offensive and equally ineffective, and both would express Trump's deeply held suspicion of Latinos."

On the other side, top Republicans, including Senate Majority Leader Mitch McConnell (R-Ky.) and House Speaker Paul D. Ryan (R-Wis.), praised the plan as a constructive step forward, and some Senate hard-liners who have consulted closely with the White House sought to help build support.

"The president's framework is generous and humane, while also being responsible," said Sen. Tom Cotton (R-Ark.), an immigration hawk who has been in frequent contact with Trump.

Senior White House officials, who briefed reporters on the details, described the plan as the result of months of meetings with lawmakers after Trump terminated the Obama-era Deferred Action for Childhood Arrivals program, which had provided work permits to 690,000 dreamers. The bulk of their permits will begin to expire March 5.

The officials said that the president hopes McConnell will bring a bill based on the framework to the floor the week of Feb. 6, just days before a Feb. 8 deadline for a must-pass spending bill to keep the government open. Many Democrats and some Republicans said they will not support a long-term spending bill without an immigration deal.

"This is kind of a bottom line," said one senior administration official who, like the others, spoke on the condition of anonymity to discuss a proposal that had not been made public. "This is the president's position. Then it goes to the Hill, and they digest it and develop a bill they think can pass. . . . If it's realistic, he'll sign it. If not, he won't."

The details of the White House plan come a day after Trump told reporters that he would be open to an immigration deal that includes a path to citizenship for dreamers.

Trump and senior aides indicated Wednesday that the citizenship path would be limited to the 690,000 dreamers in the program when the president terminated it.

Officials said Thursday that the citizenship path would be open to anyone who had been eligible for DACA, even the hundreds of thousands of dreamers who never applied. The Migration Policy Institute has estimated that up to 1.3 million dreamers were eligible for DACA last year, with another 600,000 who could become eligible if they met certain requirements.

White House officials acknowledged that the House would likely consider a separate immigration proposal that could take a more conservative approach, potentially setting up a cross-chamber conference for a final deal that would come to Trump's desk.

"We're grateful for the president showing leadership on this issue and believe his ideas will help us ultimately reach a balanced solution," said Doug Andres, spokesman for Ryan.

But the White House proposal is likely to be treated in the Senate as a starting point in the debate, not the bottom line. Conservative news sites hammered Trump for his support of a path to citizenship, with Breitbart News calling the president "Amnesty Don" in a headline Thursday.

Democrats will be under pressure from immigration groups to reject the proposal.

"This is going to be dead on arrival. We are going to oppose it fiercely," said Frank Sharry, executive director of America's Voice, an immigrants rights organization.

White House aides said the plan aimed to provide Congress greater clarity over what Trump would support.

White House aides dismissed the notion that Trump's proposal was too hard-line for Democrats and some moderate Republicans. One official pointed to the failed attempts by Congress to pass sweeping immigration bills under Presidents George W. Bush and Barack Obama and said Trump's proposal aims to appeal to more conservative members by beefing up border security and limiting family immigration, which the president has referred to as "chain migration."

The White House plan notably does not allow parents of dreamers to remain in the country, an issue that is likely to inflame tensions. A proposal from Sens. Lindsey O. Graham (R-S.C.) and Sen. Richard J. Durbin (D-Ill.), which Trump rejected this month, would have allowed parents of dreamers to stay in the country on renewable permits but not seek legal permanent residency.

Another potential sticking point centers on Trump's proposal to end a diversity visa lottery that has awarded about 50,000 green cards annually to foreigners from countries with low immigration rates to the United States, including many African nations.

Under Trump's plan, those visas would go toward speeding up a waiting-list backlog of up to 4 million family members of U.S. citizens who have already applied for green cards. Trump would allow those family members' applications to be processed even as he terminates some family categories.

The Durbin-Graham proposal would have reallocated the diversity lottery visas to some of the hundreds of thousands of immigrants already in the United States who have temporary protected status allowing them to remain because it is deemed too dangerous for them to return to their home countries. Trump has declared an end to TPS status for immigrants from El Salvador, Haiti and other countries, angering Democrats.

When asked whether Trump would support a "DACA-only bill" if the Senate fails to pass the White House proposal, one aide replied: "This is DACA" and held up a one-page summary including border wall money and legal immigration cuts.

Josh Dawsey and Michael Scherer contributed to this report.