Story highlights Deal says no green cards for undocumented immigrants before border security steps

GOP Sen. Flake expects a dozen more Republican votes due to the changes

The deal would double the number of border patrol agents

The goal is to increase pressure on House Republicans to pass an immigration bill

A border agent every 1,000 feet, every hour of every day, supported by 700 miles of fencing along the Mexican frontier.

No green cards for the 11 million immigrants living illegally in America until those steps and others to enhance border controls are taken. And none of it increases the federal deficit or debt.

A bipartisan group of senators unveiled a compromise on Thursday intended to ensure Senate passage of a major immigration reform bill with enough Republican support to persuade the GOP-controlled House to also take up the measure that is a priority of President Barack Obama.

The bipartisan amendment would require 20,000 more border agents, completing 700 miles of fence along the boundary with Mexico, and deploying $3.2 billion in technology upgrades similar to equipment used by U.S. forces in Iraq and Afghanistan.

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The proposal, negotiated by a group of senators from both parties known as the "Gang of Eight," also insists on stronger worker verification and border entry-exit controls.

Only after those five conditions have been met and verified by the Department of Homeland Security can undocumented immigrants get permanent residency, supporters said.

GOP Sens. John Hoeven of North Dakota and Bob Corker of Tennessee introduced the compromise amendment, saying it incorporated proposals from other senators to try to fix a broken immigration system.

Hoeven noted the bill would allow immigrants now living illegally in the country to get temporary legal status as "registered provisional immigrants," but the increased security measures must be in place before they can get green cards to make them permanent residents.

Republican Sen. Lindsey Graham of South Carolina, a member of the "Gang of Eight," noted it would take "a couple of years" to train and deploy the new agents in an expansion that would almost double the current force.

The Department of Homeland Security would verify when the triggers for improved border security had been met to begin issuing green cards, Graham added.

He also said the measure would include increased fees and other mechanisms to pay for the cost expected to exceed $30 billion, citing a Congressional Budget Office report that showed the broader immigration measure would bring in $197 billion in revenue over the next 10 years.

"I am very pleased to support what I think is the most dramatic amendment in the history of our country to get our borders secured," Graham said.

However, some conservative GOP senators remained skeptical that the proposal would address their concerns.

Alabama Sen. Jeff Sessions said the compromise means "amnesty will occur," and he complained that despite all the promises made by its sponsors and supporters, no written version had been produced so far.

Sessions also noted that the compromise only came about in reaction to revelations about shortcomings in the original bill uncovered by critics including himself.

Roy Beck, president of a group that opposes the immigration reform measure, called the compromise "a desperate political move by pro-amnesty forces to provide cover to pass a bill that would otherwise not pass."

The amendment "allows the massive increase in foreign workers that the CBO says will lower American wages and increase unemployment," said Beck, president of NumbersUSA.

In contrast, GOP members of the "Gang of Eight" said they supported the plan.

Veteran Sen. John McCain of Arizona said Congress must resolve the issue of 11 million undocumented immigrants "living in the shadows" under the current broken system.

Citing the nation's "Judeo-Christian" tradition, McCain asked if it was "in our nation to come together and pass this legislation and not come up with reasons for not doing it."

Arizona Sen. Jeff Flake noted that he expected the compromise amendment would persuade a dozen or so Republicans to support the overall bill.

"This border security package will bring on a number of Republicans," Flake said. "We've always said the bill would be improved through the process and this is part of that improvement."

Supporters want to win at least 70 votes in the 100-member Senate, hoping such a solid majority would give the measure much-needed momentum in the GOP-controlled House.

Earlier this week, House Speaker John Boehner rejected having the GOP-controlled chamber vote on an immigration measure if it needed Democratic votes to pass.

"I don't see any way of bringing an immigration bill to the floor that doesn't have majority support of Republicans," Boehner, R-Ohio, told reporters.

Conservative Republicans oppose the plan as written because it provides a pathway to citizenship for most of the 11 million immigrants living illegally in the United States.

They call such a move an amnesty for lawbreakers, and they fear the influx of likely Democratic voters in future elections.

In addition, they reject the measure as a "big government" approach that will increase pressure on entitlement programs such as Medicare and Medicaid.

More moderate GOP leaders and legislators believe Republicans risk worse electoral damage if the party is blamed for blocking immigration reform.

In last year's election, Obama won a strong majority of the Hispanic vote in defeating GOP nominee Mitt Romney, and Republican strategists warn of similar results if the party is considered hostile to immigrants.

Conservative Sen. Marco Rubio of Florida, another Republican in the "Gang of Eight," said the alternative to immigration reform was keeping in place a broken system that has led to problems cited by opponents of the legislation.

The first-term senator, who's widely considered a potential 2016 contender for the GOP presidential nomination, told CNN that he's not concerned about the political risk of tying his name so closely to such controversial legislation.

"The easiest thing to do politically is just not deal with the issue -- you know, give a couple speeches, and not play and get involved and try to solve it," Rubio said. "I'm dealing with this because this is hurting our country badly."

Earlier, Vice President Joe Biden made an impassioned appeal for immigration reform on Thursday, telling a prayer breakfast with Latino leaders that "it's time we pass fair -- firm but fair -- reforms to bring these 11 million undocumented immigrants out of the shadows."

Calling the legislation "the morally right thing to do," Biden said "it is not hyperbole in my view to suggest, that for the people we care about, we're at the cusp in our generation of making hope and history rhyme."

A CNN/ORC International poll released this week showed that a solid majority of respondents -- 62% -- think border security should be the main focus of immigration legislation, with 36% saying the legislation should emphasize a path to citizenship for immigrants living illegally in the country.

The poll showed Democrats divided evenly on the question, while independents and Republicans strongly called for a focus on border security.