Washington ? Two top Marine Corps officers acknowledged Tuesday that they waited two months to issue a contract for armor kits to protect the undersides of Humvees after promising to do so earlier this year.

Testifying before the House Armed Services Committee, Gen. William L. Nyland, the assistant commandant of the Marine Corps, and Brig. Gen. William D. Catto, the chief of Marine Corps Systems Command, attributed the delay to a “lack of leadership.” They assured the committee that all Humvees and military trucks that the Marines used in Iraq would be adequately protected by December.

Improvised explosive devices, as the military calls homemade bombs, have become the biggest killer of U.S. troops in Iraq this year.

Lawmakers expressed frustration Tuesday that troops don’t have enough protective armor and other equipment to protect them from the explosives, which typically are jury-rigged from cast-off artillery shells and other munitions.

“This is a sad day for us,” Rep. Duncan Hunter, R-Calif., the committee’s chairman and the father of a Marine who’s served in Iraq. “It’s a sad day because you’ve got Marines out there in the theater who are fighting with a great sense of urgency for our country … but the bureaucracy you gentlemen have back here … is resistant to moving this thing with a sense of urgency.”

Rep. Ike Skelton, D-Mo., noted that “for nearly two years we’ve watched the services struggle to provide enough protective armor” without success. He suggested that more congressional oversight was in order.

“Needless to say, I’m sorely disappointed,” he said.

Catto, who has oversight of all Marine Corps equipment issues, took the blame for the delay. “This is a lack of leadership on my part for not paying more attention to that specific contract,” he said.

Nyland also accepted fault, but said increased production of armor kits in the United States had made up for the shortfall.

“I acknowledge that we took our eye off the ball on that contract,” he said. “But we had a parallel course at the same time … and we have in fact now almost 400 underbodies on the ground for the purposes of installation at the unit level.”

At least 34 Marines have died from improvised bombs in Iraq this year, according to Iraq Coalition Casualty Count, a Web site that tracks and classifies casualties based on Defense Department news releases. Overall, 155 American military deaths have been attributed to such bombs so far this year, more than half of U.S. combat fatalities.