Big tech firms and private prisons represent two industries vigorously lobbying to influence the scope of legislation aimed at overhauling U.S. immigration policy, a political priority in Washington.

Microsoft, Facebook, and Intel want lawmakers to support increasing the number of visas available to highly skilled workers, according to an analysis by the Center for Responsive Politics, which tracks the influence of money in politics.

Others, like Corrections Corporation of America, which builds detention facilities to house illegal immigrants, have contributed heavily to the campaigns of lawmakers who take tough stances on the issue.

In all, 359 lobbying clients pressed their positions on immigration reform to officials at nearly every level of government, including the White House, Congress and the Homeland Security Department, according to the analysis for 2012. The figure is up from the 317 clients lobbying on immigration from the previous year.

It is difficult to track exactly how much each spends on lobbying an issue, campaign finance experts say. However, tracking the number of times something specific is mentioned on disclosure reports indicates its importance to a company or industry.

"They're not spending this money just willy-nilly. They have a goal and they're trying to achieve that goal legislatively," said Steve Ellis, vice president of Taxpayers for Common Sense, a watchdog group.

"You have to be sure they're writing the legislation for the right reasons and not just trying to benefit one particular company," Ellis said.

President Barack Obama underscored the need for comprehensive immigration reform earlier this year stressing the need to better enforce related laws, provide a path to citizenship for the more than 11 million undocumented workers already in the country and reform the legal immigration system.

The so-called "Gang of Eight" in the Senate and a similar bipartisan group in the House are working on crafting a reform framework leading up to what could be one of the year's biggest legislative showdowns.

"The reason immigration is on the table now is the outcome of the last election," said Judith Gans, manager of the immigration policy program at the University of Arizona. "No political party likes to lose and the Republican party realized that their unfriendly stance toward immigrants was creating a coalition in the Democratic Party."

The upcoming legislative battle will create winners and losers, and businesses are doing everything they can to ensure they can influence the outcome.

"We will see Congress make it easier for that high-skilled, cutting-edged talent to come to the U.S. But if they don't address the channels for low skilled workers to come to the U.S., illegal immigration will continue," Gans said.

The nation's tech sector, which has come to rely strongly on highly trained and science-savvy foreign workers, has long had a vested interest in immigration policy.

When Congress failed to take action on the issue, big business and their lobbyists turned their attention to agencies and lawmakers for support in increasing the number of H-1B visas.

Those are used by companies to temporarily employ foreign workers with special skills.

But H-1B visas are capped at 65,000 annually for those with undergraduate or professional degrees. Another 20,000 are reserved for candidates with graduate-level credentials. The competition is fierce for slots and available caps are often exhausted quickly.

Microsoft spent $8 million last year in broader lobbying efforts and filed 33 disclosure reports dealing with immigration --- twice the number of lobbying reports of companies like Intel.

Microsoft, which contributed $814,645 to President Barack Obama's re-election campaign, submitted four reports showing that some of its lobbying efforts were directed at the executive office of the president.

The company also lobbied Congress and 22 other federal agencies and offices on issues like corporate tax reform and antitrust law.

But the second-highest number of lobbying reports filed by the company dealt with immigration.

Other tech companies also lobbied heavily.

Intel spent $3.7 million in overall lobbying and filed 16 reports. Facebook spent $3.9 million in overall lobbying and filed eight reports, including those for lobbying the executive office of the president and the White House.

"The reality is that in the United States, we are creating unfilled jobs faster than we are creating new filled positions," Brad Smith, Microsoft's executive vice president and general counsel, said during a speech at the nonpartisan Brookings Institution last year about his industry's need for more highly-skilled workers.

Tech companies say they look for qualified U.S. workers first, but are having a tough time finding college graduates with the needed skills to work in science and technology fields.

A significant portion of these corporate workforces are comprised of well educated, highly-skilled foreign nationals who are highly sought after and can only go to work for an American company if they are extended an H1-B visa.