Byron York

Despite the bill's far-reaching scope and extraordinary level of detail, Democrats are trying to move it through the Senate with unusual speed. This week marks a new stage of that effort. On May 9, the Senate Judiciary Committee began considering amendments to the bill -- work that chairman Sen. Patrick Leahy, D-Vt., has promised will be finished, with a final committee vote, by the end of this month. After a few initial sessions, Leahy said recently, the committee will meet "every day and evening" to make the deadline.

Democrats are hurrying because they can. They outnumber Republicans 10 to eight on the Judiciary Committee, which means Democrats can by themselves shoot down any unwanted amendments. In addition, two of the committee's eight Republicans, Lindsey Graham and Jeff Flake, are members of the Gang of Eight, giving pro-reform forces even more strength, should they need it.

Sure enough, in the first session devoted to considering amendments, Graham and Flake joined with a unanimous Democratic majority to defeat several Republican-sponsored border security proposals.

When it's finished, the bill, with whatever amendments Democrats on the Judiciary Committee approve, will go to the full Senate, where Majority Leader Harry Reid, D-Nev., has vowed to keep the rush on. Again, Democrats enjoy another big numerical advantage, with 55 members. Add to that the four Republicans on the Gang of Eight, and you've got 59 in a body in which 60 votes are required to overcome a filibuster. Getting that 60th vote from Republicans still panicked by last November's election results will likely be no problem for the pro-immigration forces.

Unless things change. One key indicator of immigration reform's prospects in the full Senate will be positions taken by Democratic senators -- Mark Pryor, Mary Landrieu and Jon Tester -- who voted against reform in 2007. Back then, they were voting against a Republican president, George W. Bush, who favored reform. Now, they would be crossing a president of their own party.

In addition, there are other Democrats up for re-election next year in states won by Mitt Romney in 2012. Together, what they decide to do could shape the final bill.

But the bottom line is that in the Senate, Democrats have an advantage that will be hard to beat. That makes what happens in the Republican-controlled House, which still has not come up with a plan, crucial to the future of immigration in America.

Byron York

Byron York, chief political correspondent for The Washington Examiner