Air Force Secretary James G. Roche opposed formally reviewing alternatives to a lucrative contract for the production of new military refueling planes by Boeing Co. despite Pentagon regulations requiring such a review, according to e-mails disclosed yesterday by an opponent of the deal, Sen. John McCain (R-Ariz.).

The documents shed light on why the Air Force refused to conduct the review for three years, until Defense Secretary Donald H. Rumsfeld ordered it to do so on May 25. He acted after two studies -- by the Defense Department's inspector general and the Defense Science Board -- faulted the Air Force for failing to follow contracting regulations, and after the top Air Force official who negotiated the deal was indicted on charges of violating conflict-of-interest rules.

McCain has depicted the contract as a waste of money, and he held up the confirmation of several senior military officials until White House counsel Alberto R. Gonzales agreed to let him see some of the Air Force's internal documents. In a July 28 letter to Rumsfeld, McCain quoted the e-mails and said they called into question the Air Force's credibility and had convinced him that "the conduct of Air Force leadership . . . has been unacceptable."

An Air Force spokesman, Col. Jay DeFrank, declined to specifically address McCain's letter to Rumsfeld but said that "the Air Force has to operate these planes, and we have a vested interest in making sure we look at the best alternatives, with the utmost integrity."

The Air Force's $23.5 billion plan to rent at least 100 Boeing 767 jets as tanker aircraft is the costliest government lease in U.S. history and was the subject of substantial debate in the Bush administration.

It was strongly opposed, at least initially, by the Office of Management and Budget. But top Air Force officials embraced the idea after a Boeing lobbying campaign that reached the White House and gained the support of key lawmakers.

The contract ran into trouble when McCain, the chairman of the Senate Commerce, Science and Transportation Committee, threatened last summer to subpoena Boeing's internal documents. In response, Boeing turned over e-mails that laid bare the scope of its lobbying campaign for the tankers -- a program meant to sustain the production line for commercial Boeing 767s at a moment of declining airline orders.

The Air Force had contended that existing KC135 tankers were aging so rapidly that their replacement was urgent, rendering an analysis of alternatives too time-consuming. It also pointed to a demand in congressional legislation, inserted by Boeing supporters, that it spend funds only on the Boeing 767.

But the inspector general said the Air Force could not prove that the new planes would meet its requirements, and the Defense Science Board said the old planes were not aging as rapidly as asserted.

Roche, in one e-mail referring to outside pressure for an analysis of alternatives, or AOA, wrote a deputy in August 2003: "Agggggg, stop the nonsense! Don't even begin to start an unnecessary AOA at this point. All this would do is give the enemies of the lease an excuse from DOD [Department of Defense] to delay."

Roche also expressed concern in his e-mail that a postponement might "honk off the Appropriators." He was apparently referring to lawmakers such as Senate Appropriations Committee Chairman Ted Stevens (R-Alaska), who has championed the lease since 2001. In an e-mail reply, Deputy Undersecretary of Defense Michael W. Wynne said he shared Roche's concern: "What started this flurry of activity? I'd hate for our story to change."

In an e-mail sent in November 2002 to senior defense officials, Roche expressed certainty that a review of alternatives would be a waste of time. "A formal AOA will cost money, delay the program two years, and still come up with the same answer we have today," he wrote. "What's left to study?"

After Rumsfeld ordered the analysis this year, the Air Force assigned the task to Rand Corp. That move provoked new complaints from McCain, who pointed out that the think tank receives about $25 million annually in Air Force funding and said it therefore cannot be considered "an entity independent of the Air Force."

In his letter to Rumsfeld, McCain drew support from an internal complaint by Eric Coulter, a senior official in the Pentagon's office of program analysis and evaluation. "I do not support RAND as the sole source or lead to conduct the congressionally directed independent tanker AOA," Coulter wrote in August 2003.

He wrote that the Air Force would "get a better, more objective product" from the department's own think tank, the Institute for Defense Analyses. The advice was not taken, and the results of the review are due by November.