WASHINGTON -- The Bush administration is expected next month to choose an industry consortium to erect a high-tech security shield along the U.S. borders, launching one of the federal government's most ambitious public-works projects in years.

The Department of Homeland Security calls the proposed Secure Border Initiative Net the "most comprehensive effort in the nation's history" to gain control of more than 6,000 miles of border with Mexico and Canada as well as 2,000 miles of coastline.

SBInet is a centerpiece of President Bush's efforts to fortify the porous U.S.-Mexico border at a time when Congress is locked in a struggle to overhaul the nation's immigration laws. Administration officials say they intend to proceed with the security net regardless of the outcome of the debate over immigration legislation.

The multibillion-dollar undertaking has ignited an intensely fought contract battle among industry teams headed by four leading defense companies -- Boeing, Lockheed Martin, Northrop Grumman and Raytheon -- and Ericsson, the Swedish-based telecommunications giant with U.S. headquarters in Plano, Texas.

Collectively, the teams are composed of nearly 40 companies in more than 15 states, a broad and diverse lineup that includes global engineering firms, niche industries adept at biometric identification or surveillance, and blue-ribbon aerospace corporations that are better known for churning out warplanes, tanks and missiles.

Among the states vying for a piece of the action are California, Missouri, Florida, Minnesota and Pennsylvania. Los Angeles-based Northrop Grumman's teammates include HNTB Corp., a nationwide engineering and architectural firm headquartered in Kansas City, Mo., and Identix, a top-tier biometric company in Minnetonka, a suburb of Minneapolis.

The U.S. Customs and Border Protection, a branch of the DHS, is expected to announce a winner by Sept. 30.

As envisioned by Homeland Security Secretary Michael Chertoff, SBInet would marry industry expertise with the 42,000-employee Customs and Border Protection to create a wall of technology, manpower and infrastructure over the next six years. The initial cost is projected at $2.5 billion, but the price ultimately could be much higher.

Although Deputy Homeland Security Secretary Michael P. Jackson told industry officials that the project is "not about simply buying gizmos," much of the attention has focused on the potential mix of technology. Most of the proposals include state-of-the-art sensors, mounted cameras, unmanned aerial vehicles, radar and other surveillance hardware.

Calls for toughening the border have intensified with the approach of the fifth anniversary of the Sept. 11 terrorist attacks and the recent alleged terrorist bomb plot in Britain. But the project has come under heightened scrutiny on Capitol Hill after a congressional report last month blasted DHS procurement polices.

The bipartisan report, released by Republican and Democratic leaders of the House Government Reform Committee, identified $34.3 billion worth of DHS contracts marred by significant overcharges, wasteful spending or mismanagement. The troubled projects included a largely ineffective camera-surveillance system along the Mexican and Canadian borders.

Rep. Henry Waxman, D-Calif., complained that SBInet could be exposed to the same problems, contending that the DHS is giving industry too much latitude in determining how the system should be tailored. "That's not governing," he said. "It's utter incompetence, and it's going to cost the taxpayers billions."

From the bidders' vantage point, SBInet could create thousands of jobs and underscore the defense industry's expanding transition into homeland security. Tools of war -- such as radar and satellite surveillance -- easily can be redirected into the campaign to guard the home front.

"We see it as an increasing market," said John W. Douglass, the president and chief executive officer of the Aerospace Industries Association. "Many of the technologies that make you a successful aerospace contractor would also make you a successful homeland-security contractor."

Several of the team members started preparing for the project more than two years ago, when the DHS was considering a since-abandoned border initiative called America's Shield. Team representatives have spent months on the border, and several of the bidders have set up remote border-area test sites to evaluate their equipment.

Nearly 60 potential bidders expressed interest in the project before the DHS winnowed the field to the five rival teams. Universities in Texas, New Mexico and Arizona are aligned with several of the teams, reflecting academia's growing expertise in homeland security and border demographics.

Bidders made oral presentations over the past two weeks and have until Monday to update their proposals. One major defense contractor, L-3 Communications, headquartered in New York, is effectively competing against itself, with units positioned on three teams.

While SBInet bristles with opportunity, the winning team will face immense obstacles in trying to create a leak-proof "virtual wall" traversing rugged desert terrain in the south and mountainous, wooded landscape in the north. The challenges probably will include property-rights disputes and environmental issues.

Sensors and cameras have been operating along the borders for years; the SBInet team will be charged with building an integrated and modernized system tying all the pieces together. In addition to technology, the industry team will provide contract personnel for non-law enforcement jobs and train government agents to adapt to the new system.

In a January briefing, Jackson urged industry officials to be innovative without straying "onto the wacky edge of creativity." Most proposals call for a network of thousands of sensors that would detect movement, sound and in some cases smell.

The sensor then would flash an alarm on a computerized map in a command-and-control center, where an operator would train a long-range mounted camera on the site to determine whether an animal or a human intruder tripped the alarm. If necessary, agents would be dispatched. Several, if not all, of the teams would augment the protection with unmanned surveillance aircraft and, in some cases, high-altitude surveillance balloons.

The project could unleash a construction boom along the Mexican and Canadian borders as the winning consortium erects buildings, roads and an as-yet-unspecified stretch of barriers and fences to complement the high-tech shield.

Accordingly, most of the teams bristle with engineering and architectural talent, such as HNTB and Fluor Corp., a 35,000-employee international construction company that moved its headquarters from California to Irving, Texas, this summer. Fluor is a member of Ericsson's team.

DHS officials expect the work to encompass thousands of suppliers and subcontractors. Lockheed Martin, for example, held community meetings in seven cities along both borders, meeting with more than 350 subcontractors. More than 650 companies have registered on its Web site.

For all the players, SBInet offers a chance for a giant leap into an already burgeoning government market. Since the DHS was created in 2003 from the consolidation of 22 agencies and departments, procurement spending at the department rose from $3.5 billion to $10 billion in 2005, according to the House Government Reform Committee.

Perot Systems of Plano, Texas, founded by Dallas billionaire H. Ross Perot Sr., already has 700 employees working with the DHS under its four-year-old government services division; it would supply support personnel to command-and-control centers if its Boeing-led team wins the contract. Many other companies also have at least a toehold in DHS business.

The shield is a dominant component of the Secure Border Initiative to stem the flow of illegal immigrants, which Chertoff announced last November. More than 1.2 million illegal immigrants were arrested in 2005, nearly all on the southern border.

Mark Reed, the president of Border Management Strategies in Tucson, Ariz., and a member of the Raytheon team under BAE Systems, said the proposed security shield marked an unprecedented commitment to construct high-tech "eyes and ears" on the border.

"At the end," he said, "what's important is that the taxpayers end up with a product that works."