4 major reforms in the Senate's immigration bill

After months of painstaking negotiations punctuated by public disagreements among lawmakers and interest groups, a bipartisan group of senators working to craft a compromise on immigration reform will unveil their handiwork on Tuesday.

It hasn't been easy, but it's almost here. What is it, exactly?

The bill, in broad strokes, would tighten border security, modernize the visa system, and crack down on employers who hire undocumented workers. It would also extend a path to citizenship to many of the estimated 11 million undocumented immigrants living in America.

That's what we know. What we don't know is how much of the fine print is subject to the whims and amendments of an unpredictable Congress. Senators involved in drafting the plan have said their bill is only a "start," and there's every reason to believe the legislative process will change the finished product.

Even so, here's what will be included in the bill to be revealed on Tuesday, according to the senators who have written it:

Tightened border security

The bill will include a number of measures to achieve "real border security, including fencing," said Sen. Marco Rubio, one of the "gang of eight" senators working on the compromise, Sunday on CNN's "State of the Union."

The proposal will also set metrics to measure how secure the border is, and it includes safeguards designed to ensure that those metrics are achieved.

"If the Department of Homeland Security does not secure the border, does not meet the metrics of 100 percent awareness [of illegal border crossings] and 90 percent apprehension [of those crossing the border illegally] within in the first five years, then they lose control of the issue," Rubio explained on CNN. "Then it goes to a border commission made up of people that live and have to deal with the border and they will take care of that problem. And it'll be funded to ensure that that happens"

Sen. Dick Durbin, D-Ill., another member of the bipartisan group, explained on "Fox News Sunday" that the bill also provides additional money for border security if the metrics are not achieved. We have invested billions of dollars into border enforcement," he said. "And yet, we're saying that if we don't meet all the measurements, all the goals that we've set in years to come, we'll put more in, more investment there. "

On CBS' "Face the Nation," Rubio emphasized that border security doesn't only affect immigration. "The border is really about our sovereignty as a country, about our ability to protect our borders and who gets access to our nation," he said. "The fact of the matter is that, while I am not in favor of a housekeeper or a landscaper crossing the border illegally, what keeps us up at night is the worry that a terrorist can come across that border one day...And so this addresses that as well."

Modernized visa system

The bill would update America's visa system, monitoring the future traffic of immigrants during both departure and arrival to ensure that nobody overstays their welcome.

Touting what he called an "entry-exit system," Rubio explained on CNN, "40 percent of our immigrants are people that enter legally and then they overstay their visas. And we don't really know who they are, because for the most part we only track when people come in, we don't track even when they leave."

With this bill, "we are going to have an entry and exit system to track visas," he said on ABC's "This Week"

The proposal would also expand the number of visas available to high-skilled immigrants, particularly those educated in science, technology, and engineering, "who could actually create jobs," said Sen. Chuck Schumer, D-N.Y., another member of the bipartisan gang, on "This Week."

"Look what we do now - We turn away people who could actually create jobs in America," said Schumer, citing a study from the conservative Cato Institute that said found "this is going to be a shot in the arm for our economy because we'll take people in who will create jobs."

In recent years, the applications for H1-B visas, which are available to high-skilled workers, have far exceeded the number of open spots, forcing the government to literally stage a lottery to distribute them. The Associated Press reported last week that the senators' compromise could more than double the number of annually available visas, from 65,000 today to as many as 150,000.

Finally, in accordance with an agreement between business and labor groups, the bill would set up a guest worker program that aims to admit migrant laborers to work in a variety of low-skilled fields while safeguarding domestic job-seekers from an influx of cheap foreign labor.