The U.S. Senate has killed an overarching amendment to the Gang of Eight's immigration bill, but a new amendment that would double the size of the U.S. Border Patrol and require 700 miles of fencing along the border is in the works. NBC News reports:

By a vote of 54-43, the chamber voted to table — or effectively kill — the legislation by Republican Sen. John Cornyn of Texas that would have instituted new border metrics and required those goals to be met before undocumented workers can apply for green cards.

The vote came as a bipartisan group of senators have reached an alternative agreement to strengthen border security, a breakthrough agreed to both by Republicans seeking more border security and the bipartisan “Gang of Eight” that originally drafted the legislation. Democratic leaders had said after Cornyn introduced his amendment that that measure was a "poison pill," and Vice President Joe Biden told attendees at a Hispanic prayer breakfast Thursday that the Cornyn measure was "one of the meanest amendments that will come up in the Senate."

Sen. John Cornyn, pushing for his border security amendment Wednesday, compares the Gang of Eight's immigration plan to an illegal immigrant amnesty ruling from 1986.

The senators involved in the new compromise — Republicans John Hoeven, N.D., and Bob Corker, Tenn., who have been working with Gang of Eight members Sens. Chuck Schumer, Bob Menendez, John McCain and Lindsey Graham — have dubbed it the "border surge" plan; they're preparing a Thursday announcement.

Senate aides from both parties told NBC News that the agreement would double the size of the border patrol and require 700 miles of border fencing. The group has also compromised on a series of other issues, including the E-Verify program for businesses and benefits.

The New York Times has more details here.