Tension between these two dimensions permeates the debate. Conservative Republicans, especially in the House, zero in on border protection. Moderates in the GOP and most Democrats favor augmenting enforcement with guest worker programs designed to help the country’s approximately 11 million undocumented workers become citizens—a move conservatives pejoratively label "amnesty."

The House approved a bill in December that dealt exclusively with cracking down on illegal immigration, in part by making illegal status a felony and sanctioning a 700-mile fence along the U.S.-Mexico border. Senate efforts to produce a bill failed during the first week of April, clouding the prospects for congressional approval of immigration legislation this year.

Sen. Mel Martinez, R-Florida, asserts that a guest worker program is needed to help his state’s agricultural, construction and hospitality industries fill open positions. "A border-security-only bill would leave their workforce needs unmet," he says.

Bills in both the House and Senate would require companies to verify the identity of each of their employees and would impose hefty fines and criminal penalties for hiring illegal immigrants. Included in the Senate Judiciary Committee bill are provisions for 10,000 new work site enforcement agents (2,000 each year for the next five years) and 5,000 new fraud detection agents (1,000 each year for the next five years).

Such provisions indicate that the days of reviewing a résumé, interviewing and hiring without investigating residency are nearing an end.

"The question is, when does the verification take place—during or after a hire?" says Terrence DeFranco, CEO of Edentify, a provider of fraud detection technology. Further, "It’s a very, very expensive proposition," he says.

Building an electronic employment verification system to screen 54 million new hires annually as well as the rest of the 146 million U.S. workforce would cost $11.7 billion, according to the Government Accountability Office. Businesses would pick up most of that bill. And the larger the workforce, the more a company will have to invest in the process. The cost per employee may range from $10 to $50, according to Bonnie Gibson, managing director of operations and cross-border employment law at Littler Global.

Immigration reform may make another proposition easier—finding enough skilled workers for high-tech positions. The Senate was expected to pass a bill that would increase the annual cap on H-1B visas for high-tech workers to 115,000 from 65,000.

It also would exempt workers with advanced degrees in science and math from green card caps and make it easier for foreign students with high-tech majors to stay in the country. It also would more than double the cap on employment-based green cards, while exempting spouses and children from counting against the limit.

With H-1B slots filling up, companies are pleading for more visas. When an engineering firm recruits on a college campus, usually at least half its interviews are with foreign-national students who need work visas to stay in the country, says Rodney Malpert, director of immigration services for Littler Global.

But increasing employment visa caps may fall by the wayside during what will likely be a contentious House-Senate conference in the middle of a volatile election year.

"This is a crucial time for companies to get involved in the debate," says Gregory Wald, an attorney with Squire, Sanders & Dempsey. "On many levels, companies should be pushing for comprehensive immigration reform as opposed to enforcement only."

—Mark Schoeff Jr.