Ross D. Franklin/AP Photo

Analysis by ABC News Senior National Correspondent Jim Avila:

The Senate Gang of 8 led by Arizona Sen. John McCain and New York Sen. Charles Schumer is poised to introduce a comprehensive immigration bill as soon as next Monday, April 8, according to sources briefed on the timetable. As Schumer, a Democrat, said over the weekend the big moving parts of a bill have been agreed to in principle and details are being worked out this week.

Labor and business have agreed on a guest worker plan, and the senators in the Gang of 8 from the right and left have agreed on how " border security" will be defined. Although Schumer did not reveal the metrics involved, sources tell ABC News the definition of a secure border will largely entail how much money will be spent on new equipment from drones to planes to vehicles, and how many new border patrol agents will be hired before "a path to citizenship" is agreed upon.

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Sen. Marco Rubio, R-Fla., warned over the weekend that after the bill is introduced there still have to be hearings and an opportunity for members of the entire Senate to add amendments. Sources close to Rubio tell ABC News he has not changed his mind on the principles of a secure border and path to citizenship agreed to in January.

The current timetable according to Hill sources is the Senate introduces its bill next Monday, holds hearings and votes by July. The House version will likely be introduced the week of April 14. The House Gang of 8 is still waiting to hear if leadership will endorse its bill. Sources close to the House members working on its version tell ABC News its version is likely to be "a couple inches to the right of the Senate's" and voted upon in the fall.

A realistic timetable for a bill emerging from the House and Senate conference would then be Thanksgiving.

That may seem like a long time for those not versed in the ways of Capitol Hill. But that is actually lightning speed. It's quite unusual for legislation to be introduced and passed in the same calendar year.