WASHINGTON — A new armored vehicle capable of protecting troops against the deadliest roadside bombs in Iraq has been successfully tested by the Pentagon and could go into production immediately, according to its manufacturer and a U.S. senator.

The vehicle, known as the Bull, has proven effective at repelling blasts from explosively formed penetrators, or EFPs. These roadside bombs have been particularly lethal in Iraq because they can pierce even heavily armored vehicles. The Bull's method for defeating these bombs is classified, said Marc King, vice president of armor operations at Ceradyne Inc., the vehicle's manufacturer.

The Army declined to comment on the vehicle because it has not issued contracts to purchase it, said Dave Foster, an Army spokesman at the Pentagon. The Marines are evaluating the Bull and its effectiveness, said Bill Johnson-Miles, a Marine spokesman.

USA Today reported that Marine Corps officials in Iraq had issued an urgent plea to bolster the armor on new vehicles being built. The request noted that Mine Resistant Ambush Protected vehicles, which the Pentagon already is scrambling to build and ship to Iraq to counter conventional makeshift bombs, need more armor to deal with EFPs.

The Pentagon has ordered 7,700 MRAPs. The Army is considering ordering an additional 17,000, according to estimates from military documents.

Sen. Joseph Biden, D-Del., criticized the Pentagon for not moving fast enough to field both vehicles.

"The ball is being dropped again," said Biden, chairman of the Senate Foreign Relations Committee. "Today, we have two main threats. ... We have proven technologies to beat these threats: the Mine Resistant Ambush Protected vehicle and the Bull."

Improvised explosive devices, or IEDs, have taken an increasingly heavy toll on U.S. troops in Iraq. Nearly 80 percent of U.S. troops killed in Iraq last month died in roadside bomb blasts, according to Pentagon records. In January, IEDs were responsible for 39 percent of deaths.

Marine Gen. Peter Pace, chairman of the Joint Chiefs of Staff, noted that there were 69 attacks by EFPs in April — the highest monthly number recorded.

King said the Bull had passed limited government tests, including most tests for survivability. The vehicle can be configured to transport troops or haul cargo, he said. King envisions the Bull to be a complement to the MRAP. "It can ... perform against the most lethal threats on the battlefield at a high probability of success," he said.

The Bull would cost about $500,000 per vehicle. By comparison, the most common version of the armored Humvee costs $150,000. The cost of the MRAPs ranges from $700,000 to $1 million, Pentagon documents show.

King said his company could produce 100 vehicles per month, but the Pentagon has not ordered any.

That irks Biden. "I'm tired of hearing that there might not be enough money," he said. "Tell us what you need to protect our soldiers and Marines, and we will find a way to pay for it."