Leahy has said the committee will take up that proposal straight away, but the Republicans led by ranking member Chuck Grassley, R-Iowa, argue that's far too fast. They want to follow the playbook from the last major immigration overhaul in the mid-1980s, when a three-year debate included 100 hours of hearings involving 300 witnesses.
Before any vote, the GOP senators requested "that the public be given adequate time, consistent with past practice in handling complex comprehensive immigration legislation, to read and analyze the contents of any such bill."
They want hearings on topics ranging from a guest-worker program to the impact of legalizing undocumented immigrants on the larger workforce to the use of biometrics in issuing visas. And they want to be able to question Homeland Security Secretary Janet Napolitano.
"If we are serious about protecting our national interest and the best interest of American workers," the letter states, "we must provide all members of the Senate, and most importantly, the public, a full and fair opportunity to become adequately informed."
Supporters of reform have argued that Congress has debated the issue for years, pointing to 2007 when Republicans rejected a proposal backed by then-President George W. Bush.
"We can't allow immigration reform to get bogged down in an endless debate. We've been debating this a very long time. So it's not as if we don't know technically what needs to get done," Obama said in an address in late January. The next day Obama told a reporter with Telemundo that he wants Congress to act this year, preferably by summer.
Lee is one of 43 current senators who were not in the body during the 2007 debate and, unlike rising GOP stars Sens. Marco Rubio of Florida and Rand Paul of Kentucky, he has not backed an eventual path to citizenship for illegal immigrants. Neither has Hatch nor any of Utah's four House members.
Lee's stance on immigration
Sen. Mike Lee was one of eight senators working on a bipartisan plan for immigration reform, but withdrew from the group in late January when all members signed on to a recommendation that combined tougher border enforcement with setting up a process for those here illegally to eventually obtain citizenship.
In a statement at the time, Lee said: "These guidelines contemplate a policy that will grant special benefits to illegal immigrants based on their unlawful presence in the country.… Reforms to our complex and dysfunctional immigration system should not in any way favor those who came here illegally over the millions of applicants who seek to come here lawfully."