And as is usually the case for companies that do big business with the government, the private prison industry is active on the lobbying front. Records from the Lobbying Disclosure Act database show that both CCA and GEO Group have regularly lobbied the House and Senate, as well as executive-branch agencies, on immigration-related matters in recent years. But both companies say that while they lobby the government to obtain contracts, they never seek to shape the policy that determines who is detained.

“It is CCA’s longstanding policy not to draft, lobby for or in any way promote detention enforcement legislation,” CCA spokesman Steve Owen said in an email. “That means CCA does not take a position on or advocate for or against any specific immigration reform legislation nor does our government relations team on our behalf.”

GEO Group spokesman Pablo E. Paez replied in an email that “the GEO Group has never directly or indirectly lobbied or advocated to influence immigration policy.”

These claims of a hands-off approach to immigration policy debates have been called into question in the past, however. A 2010 investigation by NPR found that CCA had participated in a “quiet, behind-the-scenes effort to help draft and pass” the controversial Arizona law that allowed police to demand papers from individuals who were suspected of being undocumented immigrants and lock up those who failed to provide them. Most of that law has since been struck down by the Supreme Court.

When asked whether CCA had lobbied Sen. Alexander regarding immigration enforcement or reform, Alexander spokesman Jim Jeffries replied in an email: “Corrections Corporation of America is an important Tennessee company. Sen. Alexander and his staff have hundreds of conversations a week with his constituents and he believes they are entitled not to have those conversations publicly reported.” (Throughout his career, Alexander has enjoyed close ties to CCA: his former special assistant, Charles L. Overby, sits on CCA’s board. And his wife, Honey, made an early $5,000 investment in CCA in the first part of a transaction that later came under scrutiny.)

In reply to an inquiry about whether Sen. McCain had discussed either Operation Streamline or pending immigration reform proposals with CCA, McCain spokesman Brian Rogers replied that the enforcement program “will continue whether or not Congress passes comprehensive immigration reform. Senator McCain supports Operation Streamline because it works.”

A spokesperson for Sen. Corker said he was traveling overseas and unable to respond. Sen. Rubio’s office did not respond to email and telephone inquiries.

Impact of reform unclear

While the companies insist that they do not seek to shape immigration policy, the private prison industry has at times acknowledged its business could be affected by the reform debate. “Immigration reform laws which are currently a focus for legislators and politicians at the federal, state and local level also could materially adversely impact us,” the GEO Group declared in a 2011 SEC filing. And with the White House saying its goals for reform include “expanding alternatives to detention and reducing overall detention costs,” the limited media coverage so far has focused on potential losses for the industry. “Private prisons will get totally slammed by immigration reform,” read the headline on a Feb. 2 Business Insider piece.

But any immigration reform bill will be shaped by Congress—and the impact of reform on detention and incarceration still hangs in the balance. Divisions have already emerged between the White House and the Senate’s bipartisan Gang of Eight about the crucial path to citizenship. One key difference is that the Gang of Eight—which includes McCain and Rubio—has proposed that the Homeland Security department must certify that the border is secure before any undocumented immigrants can get green cards.

One reporter, Seth Freed Wessler of the progressive media site, has suggested that as negotiations unfold, reform might even increase the numbers of immigrants being imprisoned. A concern among Democratic staffers and immigrant advocates, Wessler wrote, is that Republicans may insist on more enforcement—such as, perhaps, an expansion of Operation Streamline—in exchange for agreeing to a path to citizenship.

Provisions to expand the population facing mandatory detention and deportation—for example, adding categories such as suspected gang members—are another means by which comprehensive reform might lead to more immigrants being detained, Wessler said in an interview.

Muzaffar Chishti, director of the Migration Policy Institute’s office at New York University, said he thought it was unlikely that legislators would seek to exert much influence over executive-branch enforcement programs such as Operation Streamline and Secure Communities.

But, Chishti said, “McCain will want to stay relevant in the Gang of Eight, so he’ll want to put his preferred items in the enforcement agenda.” And in general, lawmakers “could start introducing elements in the legislation saying these are triggers that indicate the borders are secure.”

Sasha Chavkin covers political money and influence for CJR's United States Project, our politics and policy desk. He has written for ProPublica, the Center for Public Integrity, and The New York World. Follow him on Twitter @sashachavkin.