Sens. John Hoeven, R-N.D., and Bob Corker, R-Tenn., today officially announced the agreement to strengthen border security as an amendment to the "Gang of 8? immigration bill.

The two senators announced a "border surge" compromise that calls for an additional $3.2 billion spent on border security before green cards are issued to the estimated 11 million undocumented immigrants.

The money would be spent on everything from observation towers, fixed cameras, drones, helicopters and planes, mobile surveillance systems, seismic detectors and ground radar.

It also calls for 700 miles of new fencing added to the 42 miles already in place, as well as 20,000 new border patrol agents, double the current number.

It would make the secretaries of defense and homeland security and the general accounting office certify that those systems are deployed and operational before green cards are issued.

Proponents say this would provide 100 percent situational awareness, or full monitoring along the 1,900-mile southern U.S. border, and 90 percent operational control, or a 90 percent apprehension rate of those seen crossing.

The Senate "Gang of 8? and other members had reached a late-night agreement to strengthen border security provisions in their bill that they hoped would deliver the 70 crucial votes needed for the measure, ABC News confirmed Wednesday night.

No immediate vote is expected on the newly released amendment.

The Senate Gang of 8 members include four Republicans: Marco Rubio of Florida, John McCain of Arizona, Lindsey Graham of South Carolina and Jeff Flake of Arizona. The Democrats are: Chuck Schumer of New York, Bob Menendez of New Jersey, Michael Bennet of Colorado and Dick Durbin of Illinois).

Schumer said on the floor today that the "border surge plan is breathtaking in size and scope."

He credited the new deal on the recently released CBO report that found there would be more money available than initially thought.

"I'm now confident that the Senate will pass a strong bipartisan immigration bill," he said. "Great day for immigration reform for the Senate."

Some of the "gang" members had previously called amendments that would require 700 miles of fencing and 100 percent operational control "non-starters" for the bill. But today they rose in support of this compromise.

The bill, which has been debated on the Senate floor this week, has been met with resistance from Republicans who argued that the border-security measures were not strong enough and needed to become a "trigger" before the undocumented could start down a pathway to citizenship. The pathway, Obama has said, is necessary for him to sign the bill into law.

The nonpartisan Congressional Budget Office Tuesday said the legislation proposed by the Senate gang would boost the economy and lower the federal deficit.