Sen. John McCain (R-Ariz.), upset by twin Air Force maneuvers, may try to block President Bush from shifting Air Force Secretary James Roche to the post of secretary of the Army.

But placing a hold on Roche’s nomination could be risky for McCain. By holding up Roche’s departure, McCain could unintentionally delay Bush’s appointment of the second-ever female head of the Air Force at a time when the Air Force Academy is mired in a sexual assault scandal.

According to Pentagon and defense industry sources, Bush is weeks away from announcing plans to replace Roche with Barbara Barrett, a veteran of two Republican administrations who hails from McCain’s home state of Arizona.

Still, McCain may stick to his guns in order to protest what he sees as the Air Force secretary’s botched handling of the sex scandal at the Air Force Academy.

“I’m concerned about his conduct in the investigation of the Air Force,” McCain said in an interview.

Roche also riled McCain by backing a multibillion-dollar plan to lease scores of jumbo jets from Boeing to use as airborne refuelers for fighter jets and bombers — a plan McCain sees as a boondoggle.

“A lot of questions need to be answered,” McCain said. Whether or not McCain puts a hold on the nomination, he said, “depends on his answers to the questions.”

Several Senators have signaled that they may hold Roche accountable for the ongoing investigation at the Air Force Academy. “It certainly will be explored,” said Senate Armed Services Chairman John Warner (R-Va.).

Dozens of female cadets have charged that their superiors at the Air Force Academy routinely ignored reports of sexual assaults on campus.

Earlier this year, Roche responded by transferring a handful of top commanders out of the academy, a move seen as a slap on the wrist by McCain and several other Senators.

At an April hearing, McCain called Roche’s reaction “some of the most incredible evasions of responsibility I’ve seen in my 40 years of military oversight.”

He added that Roche was “totally incapable of handing” the investigation.

After the hearing, Roche agreed to an independent investigation of the scandal.

But McCain said this week that he is still not satisfied with Roche.

Meanwhile, McCain said he remains perplexed at how the Air Force could approve the deal with Boeing without a thorough investigation of alternatives.

Under a deal reached with Boeing in late May, the Pentagon plans to lease as many as 100 Boeing 767s for the Air Force to use as flying refueling stations, costing as much as $20 billion over six years.

McCain believes the plan was designed to boost profits at Boeing at a time when the company has been hit by a worldwide slump in airline orders.

He also says the Pentagon should not sign the deal until the Air Force and the Justice Department finish an investigation into whether Boeing illegally profited from insider information gleaned from two employees the company hired from rival defense contractor Lockheed Martin.

“If a company is engaged in serious allegations of wrongdoing, that should be settled before we award them a multibillion-dollar deal,” said McCain, who made the same claim in a letter he sent late last week to Defense Secretary Donald Rumsfeld.

McCain, a former Navy pilot, says the Air Force could save billions of dollars by contracting with private companies that lease air-refueling services, such as Alexandria, Va.-based Omega Air Inc.

Omega Air, which currently has a contract with the Navy, could provide the refueling services for half the price, said Omega Air President Gale Matthews, though the company currently has just a handful of planes.

Another possibility, according to McCain, is purchasing Boeing-made plans that have been mothballed by bankrupt United Airlines.

Though McCain’s attack is aimed at Roche, the controversy could cause turbulence for Barrett as she tries to land the top job at the Air Force.

Barrett is no stranger to tough landings. Years ago, she became the first civilian woman to land an F/A-18 Hornet on an aircraft carrier.

She was also the first female deputy administrator at the Federal Aviation Administration and in 1994 became the first Republican woman to run for governor of Arizona.

Barrett currently runs a business in Arizona and sits of the board of one of the largest U.S. defense contractors, Raytheon Co. She is married to Craig Barrett, the CEO of Intel Corp.

Despite her roots in GOP politics in Arizona, Barrett is not close to McCain.

When she challenged Fife Symington in the Republican gubernatorial primary in 1994, McCain backed his pal Symington — and urged Barrett to drop out.

In a 1994 interview with the Phoenix News Times, McCain denied that he threatened to punish Barrett for staying in the race but acknowledged that he told her that “there are consequences associated with causing other candidates to be defeated.”

Since losing her primary race to Symington, Barrett and her husband have remained active in politics, giving more than $73,000 in political contributions mostly to Arizona Republicans. But they have not given McCain a dime.

Instead, they helped fuel the rise of Rep. Jeff Flake (R-Ariz.). Since 2000, the Barretts have contributed $11,000 to the frequent McCain critic who — until Wednesday — had threatened to challenge McCain for his Senate seat in a primary next year.

Nevertheless, McCain said he remains close with Barrett and her husband and plans to support her nomination to the Air Force when Bush nominates her.

“I certainly would support her,” he said.