The Pentagon is inching closer to replacing the Humvee — once called the "jeep on steroids" and currently the vehicular backbone of U.S. military operations in Iraq — with the latest lightweight tactical vehicle under development.

The Defense Department next month is expected to select at least three of the seven competing teams to advance to the next phase of a multibillion-dollar competition to build a lighter, more agile tactical vehicle that can withstand roadside bombs and explosive devices.

Like the mine-resistant, ambush-protected vehicles, or MRAPs, urgently requested by the Pentagon more than a year ago, the lightweight vehicles will be equipped with V-shaped hulls to protect soldiers from the latest urban threats, while still providing maneuverability and speed.

Among the teams competing for a stake in the deal while mingling with military officials here Tuesday at a Marine Corps conference were: Northrop Grumman Corp. and partner Oshkosh Corp.; the U.S. subsidiary of BAE Systems PLC and its teammate Navistar International Corp.; General Dynamics Corp. and Humvee maker AM General; and Lockheed Martin Corp. and Armor Holdings.

The vehicles will feature technology to absorb shocks from blasts, travel 90 miles per hour, and be easier to transport into and out of battle zones compared with the heavier MRAPs. While no weight requirement has been set by the services, the vehicles must be light enough for a C-130J aircraft to transport two of them, according to industry officials.

Dan Goure, a defense analyst at the Lexington Institute, said the U.S. military could benefit from the next generation of tactical vehicles, but he questioned whether the services will be able to properly maintain an expanded fleet that already includes MRAPs, Humvees, armored Humvees and more.

The challenge for companies has been meeting all of the government's requirements for the new vehicles, while keeping in mind the weight of armor, cargo and personnel that will be needed to complete various missions.

"The requirements have driven a lot of the technological innovation," said Kathryn Hasse, director of tactical wheeled vehicles for Lockheed Martin Corp. "It's been a big technical challenge."

But such demands, companies say, will vastly improve upon the current Humvee in offering additional protection and increased capability.

"The Humvee was a good vehicle, but it wasn't designed for the missions needed today," said Kenneth Juergens, Oshkosh program director.

Craig MacNab, a spokesman for AM General, disagreed.

"The Humvees are going to be around for decades ... there are some missions that will require that vehicle," he said. "It's not as easy as it looks."

Oshkosh and Northrop claim their offering will provide the added advantage of being able to easily upgrade the vehicles as technology continues to evolve.

The deals expected to be awarded in October to three teams will get the clock started for another 27-month period, where the remaining competitors will have to undergo a testing phase. The Pentagon will then award another set of contracts to two contractors. It's unclear whether the government will award a final contract to a single company or use multiple vendors.

Each team is being asked to build a family that will include an infantry vehicle, a general purpose vehicle and a utility vehicle to support various Army and Marine Corps missions.

The services are expected to order 65,000 vehicles, which will not enter initial production until 2013.