The 2,000-mile (3,200-km) boundary between the United States and Mexico would have enough border patrol agents to station one guard every 1,000 feet (300 metres), under a compromise measure being considered by the U.S. Senate as part of an effort to pass a comprehensive immigration reform bill.
It would also provide for the completion of 700 miles (1,120 km) of fencing, observation towers, manned and unmanned aerial vehicles, radar and even seismic devices to prevent foreigners from illegally crossing the border, according to a description provided by a sponsor of the compromise.
The buildup of agents equipped with high-tech night-vision goggles, radar devices and electronic sensors was so reminiscent to some senators of past U.S. combat missions in Iraq that supporters openly boasted about the southwestern border "surge" - even as some civil liberties activists complained about border communities being turned into militarized zones.
The huge deployment is being proposed to try to assure Republicans that the border is secure under Senate legislation supported by President Barack Obama that would open a pathway to citizenship for up to 11 million undocumented immigrants in the United States.
Republicans have said repeatedly they would not support a comprehensive immigration bill unless it stopped foreigners from illegally crossing the U.S.-Mexico border.
The cost of the extra deployment is estimated to range between $40 billion and $50 billion, congressional aides said, at a time of budgetary retrenchment pushed primarily by Republicans in Congress. Whether the money is ever appropriated-and the new agents deployed would depend on future Congresses.
"I think it's overkill," said Democratic Senator Dick Durbin, who was one of the bipartisan group of senators who crafted the original bill. "This notion of doubling the number of people on the border and 700 more miles of fence is really trying to appease some Republicans who want a dramatic show of force on the border," he said.
According to a release by Senator Bob Corker of Tennessee, one of the authors of the amendment, the bill would add 20,000 border patrol agents along the southern border to the 18,500 already stationed there.
'HOW MUCH IS IT GOING TO COST?'
Many Republican senators have suggested they are open to allowing the millions of undocumented immigrants to gain legal status as long as the border is secure enough to prevent a new wave of illegal immigrants.
But the measure authored by Republicans Corker and Senator John Hoeven of North Dakota was questioned by some of the most conservative members.
"I can tell you, we don't need 20,000 border patrol agents," said Republican Senator Tom Coburn of Oklahoma.
Republican Lindsey Graham, a supporter of the bill and the buildup, said there would be a law enforcement official every 1,000 feet of the border 24 hours a day.
The numbers exceeded by four times the number proposed by Texas Senator John Cornyn, a Republican pushing hard for increased border security, which was rejected by the Senate.
"My amendment was disparaged" as a "budget buster," said Cornyn. "I was told we don't need more boots, we need technology. Now I find to my shock and amazement (supporters) saying we need 20,000 more border patrol. How much is it going to cost? That's the question."
The difference is that Cornyn's proposal would have made deployment of the agents a "trigger" before undocumented immigrants could gain legal status.