The Senate's foray into the issue began Thursday, propelled by post-9/11 worries about border security.
As the Senate begins a high-stakes debate on immigration and border security, lawmakers agree on at least one point: Something must be done to secure America's dangerously porous borders.
They are divided, though, over whether security will be improved by bringing 11 million illegal immigrants "out of the shadows" - and whether resolving their status must be part of a border-tightening measure.
Unlike previous immigration debates in Congress, this one - the first since the 9/11 terror attacks - is colored by national security concerns. And this time, the term "amnesty," a theme of the 1986 reform law, is a nonstarter.
"Congress has struggled ... with the immigration issue for the last 30 years," said Sen. Edward Kennedy (D) of Massachusetts, as the Senate Judiciary Committee began a markup of an immigration bill Thursday. "That all changed with 9/11.... Our national security now requires us to know who is entering and leaving the US. We can't afford to ignore illegal immigration any more," he added.
Unlike the House, the Senate is considering a range of options, including temporary worker programs, to deal with the status of illegal immigrants while it beefs up border security. That strategy puts the Senate at odds with the House, which is opposing a comprehensive approach at this time.
"If the Senate truly wants reform to become law this year, it must train its focus on what the House has and hasn't done," said Rep. Tom Tancredo (R) of Colorado, a leader in the anti-immigration movement and a prospective presidential candidate, in a statement ahead of the Senate markup.
If the Senate works outside the House parameters and includes an amnesty or guest-worker provision, it will "pass the buck for yet another year. Passing our security woes to future leaders at such a critical time would be a great tragedy, and one Americans will not forget," he said.