Rumsfeld, who wants Crusader canceled, told reporters that his aides are looking into reports that Army officials went behind his back to Congress in hopes that politics would overpower policy and save the Crusader.
"I have a minimum of high regard for that kind of behavior," Rumsfeld said.
Crusader is a 155mm self-propelled howitzer that critics say has been overtaken by more advanced satellite-guided artillery systems.
Rumsfeld's comments about the Army's behind-the-scenes maneuvering raised questions about the future of Army Secretary Thomas White, under political pressure as a result of contacts with Enron Corp. officials during the company's collapse last year. White had headed Enron Energy Services, a subsidiary, before he became Army secretary.
Asked if Rumsfeld still had full confidence in White, Pentagon spokeswoman Victoria Clarke said: "He has full confidence that they will get to the bottom of this, get to the bottom of any inappropriate behavior."
She added that those responsible for any such breaches "will be held accountable."
The Pentagon's chief weapons buyer, Pete Aldridge, suggested the Army had overstepped its bounds.
The Army should "let the secretary make up his mind as to what are the priorities for this department," Aldridge said. "To be on the Hill lobbying for a different approach I think is probably not appropriate."
Loren Thompson, a defense expert at the Lexington Institute, a think tank, said he thinks it likely that the flap over Crusader will be the final straw for White, a decorated Vietnam veteran.
"Mr. White has finally found a matter of principle on which to depart," Thompson said in an interview.
Col. Tom Begines, an Army spokesman, said the Army had no comment on the matter.
The conflict over Crusader is part of a wider battle Rumsfeld has waged with the Army and other services since he took office last year and pledged to transform the military to meet 21st century challenges.
"Crusader now becomes a symbol of whether Rumsfeld's priorities will prevail or not," Thompson said.
The Army considers the Crusader vital to its strategy for modernizing and transforming U.S. land forces and to a lighter, more mobile force. The Crusader is a 155mm self-propelled howitzer that has undergone initial tests of its firing capabilities and is scheduled to enter service in 2008.
The military services routinely fight to protect weapons programs from the budget ax, but service leaders are expected to fall in line with the defense secretary once he makes up his mind.