A bipartisan Senate plan unveiled Monday to overhaul the U.S. immigration system frames a pitched debate expected in Congress around the areas of border enforcement, a path to citizenship for those already in the country and the future flow of new arrivals.
The brief outline includes a call to expedite citizenship for young people brought here as children, and a path to citizenship for the more than 11 million illegal immigrants living in the United States — the issue certain to stir the greatest political fight.
Notably, the plan nods to conservatives' preference for stricter enforcement efforts by requiring that America's borders be secured before existing illegal immigrants can seek legal status.
"We have a long way to go, but this bipartisan blueprint is a major breakthrough," Sen. Charles Schumer, D-N.Y., said at a news conference attended by five of the eight senators who are crafting the plan.
Republican Sen. John McCain of Arizona, one of the signatories, pledged that the process wouldn't repeat "the mistakes of 1986," when he said an amnesty program legalized millions of immigrants but set conditions for the illegal arrivals of millions more.
The announcement came on the eve of a Tuesday speech on immigration by President Obama in Las Vegas, where the president is expected to lay out his own principles, which align with the senators' framework. Obama advisers have signaled that he could offer more details in his State of the Union address on Feb. 12.
Members of the "group of eight" senators — four Democrats and four Republicans — said they hope to complete a draft of the legislation by March and send it to the full Senate for a vote by late spring or summer.
Groups on both sides of the debate already have begun to mobilize campaigns to apply pressure on lawmakers over the coming months.
"The public is overwhelmingly on our side and on our president's side," Mary Kay Henry, president of the Service Employees International Union, told reporters Monday in a conference call with civil rights and pro-immigrant groups in support of the plan. "We think it's important for both parties to take leadership at this incredible moment. And we don't want some piecemeal solution. Reform must include a path to citizenship."
Opponents quickly criticized the plan as an amnesty program and a retread of the last overhaul bill, which failed in 2007.
Some conservatives also dismissed the provision in the new plan that would prioritize securing the borders over granting legal status. They say it mandates tracking people exiting the country by air and sea, but not by land.
"There were good reasons that  bill failed, and I think that it will apply to this bill, as well," said Rosemary Jenks of NumbersUSA, which advocates greater enforcement measures and a reduced flow of immigration. "The enforcement mechanisms are fairly meaningless and actually weakened current law."
The plan was backed by Republicans McCain, Marco Rubio of Florida, Lindsey Graham of South Carolina and Jeff Flake of Arizona; and Democrats Schumer, Richard Durbin of Illinois, Robert Menendez of New Jersey, and Michael Bennet of Colorado.
The senators' plan reflects growing agreement in both parties that any legislation must accomplish several goals, including normalizing the status of existing illegal immigrants, strengthening border enforcement, requiring verification of workers' immigration status, and increasing visas for temporary agriculture workers and those working in the fields of science and technology.
Immigration analyst Muzaffar Chishti of the Migration Policy Institute says the political environment in Washington "has never been more favorable for comprehensive immigration reform. The issue is whether there is enough political space between now and the end of the year for the mechanics of the legislation to go through."
A large and growing Hispanic population voted overwhelmingly for Obama over Republican Mitt Romney in November, and many Republican leaders have said addressing immigration law is key to beginning to capture some of those voters.
But there are several potentially deal-breaking questions unlikely to be answered right away.
The biggest is whether existing illegal immigrants would receive legal status or a path to citizenship, an issue Chishti calls "the big elephant in the room."
The White House's statement said "any legislation must include a path to earned citizenship." And Senate Majority Leader Harry Reid, D-Nev., recently drew a line on the matter, saying no legislation would pass his chamber without the provision.
Most Republicans in both chambers have declined to go as far with their support. A number of Republican senators had lined up behind an earlier blueprint offered by Rubio that favored normalizing illegal immigrants without expressly providing a citizenship path.
But on Monday, Rubio, a Cuban-American senator and potential leader on the issue in the GOP, joined the seven other senators in the bipartisan call for a "tough but fair path to citizenship for unauthorized immigrants."
The other matter is whether the reforms will be packaged in a single bill, as Obama and Democrats prefer, or divided in separate pieces of legislation as favored by many Republicans.
The Republicans' position was undercut by Jeb Bush, the Republican former governor of Florida, who argued in a recent op-ed in The Wall Street Journal for a single comprehensive bill.
Obama on Friday met with members of the Congressional Hispanic Caucus, which is expected to play a key role in the debate. The caucus, which is made up of House and Senate Democrats, had for weeks urged the White House to take a leading role.
Hispanic lawmakers have issued their own policy priorities, most of which align with Obama's and those of conservative lawmakers. They include requiring illegal immigrants to register with the federal government, undergo a criminal background check, learn English and pay taxes as conditions for obtaining legal status and eventual citizenship.
The bigger fight may come in the House, which would have to take up a Senate bill or draft its own version before the two chambers could reach a compromise in conference. Unlike the Democratic-led Senate, the House is controlled by Republicans, who have installed immigration hawks on the Judiciary Committee's subcommittee on immigration, which would handle related legislation.