By David Nather, CQ Staff

Over and over again when the Senate was debating whether to authorize the Iraq War five years ago, John McCain of Arizona spoke out against any amendment that would have restricted the president’s war powers.

“The Congress can declare war, but it cannot dictate to the president how to wage war,” McCain said when Democrat Robert C. Byrd of West Virginia tried to restrict the resolution to authorize military strikes only if there was a clear threat of attack from Saddam Hussein.

“These requirements are onerous and infringe upon the authority of the commander in chief to meet his obligations to protect American security,” McCain said when Byrd then attempted to rewrite the resolution to end the war authorization after a year.

HANGING IN: McCain, struggling all year to revive his campaign, speaks in Columbia, S.C., on April 26. (GETTY IMAGES / JUSTIN SULLIVAN)

“This body should allow the executive branch the leeway to conduct diplomacy at the U.N. — not try to micromanage it from the Senate floor,” McCain said when Democrat Carl Levin of Michigan stepped in and tried to narrow the measure to authorize the war only if the United Nations demanded unrestricted access for weapons inspectors and Iraq failed to provide it.

All of the amendments were soundly rejected.

With nearly 21 years in the Senate and four years before that in the House — much more time at the Capitol than any of the other viable 2008 candidates — McCain might be expected to have a unique appreciation of congressional oversight, and he does have a record of challenging presidents from both parties. But he also was an officer in the Navy for 23 years and has a strongly pro-military voting record, and that background leads him to argue for broad presidential authority to use military force — authority he will be sure to claim for himself if he is elected president.

Like so many other things about the famously independent-minded McCain, his balancing act on executive power makes it hard, even for those who have worked closely with him, to predict how he would come down in a clash between the White House and Congress.

“I’d have to speculate far too much,” said Anthony H. Cordesman of the Center for Strategic and International Studies, a former national security adviser to McCain on the Senate Armed Services Committee. His Senate spokeswoman, Melissa Shuffield, offers only that McCain “defends the constitutional authority of the legislative and executive branches with equal vigor.”

It’s safe to say, however, that he would not try to claim as much presidential power as President Bush has. Republican Sen. Lindsey Graham of South Carolina, who worked with McCain on a 2005 measure that banned torture and who is supporting his presidential bid, said the Bush administration’s view of executive power is “breathtaking, and not shared by Sen. McCain.”

“I think Sen. McCain would be an aggressive advocate of executive power, but not to the extent that this administration has framed it,” said Graham.

Indeed, when Republican candidates were asked during a debate in October whether congressional authority would be required for a strategic attack against nuclear facilities in Iran, McCain said he would at least consult with Congress — and obtain its “approval,” if possible.

“If the situation is that it requires immediate action to ensure the security of the United States of America, that’s what you take your oath to do, when you’re inaugurated as president of the United States,” McCain said during the debate. “If it’s a long series of buildups, where the threat becomes greater and greater, of course you want to go to Congress.”

McCain’s 2005 detainee legislation, which prohibited torture and cruel or inhumane treatment of those in U.S. custody, was perhaps his biggest and most successful challenge to Bush’s authority. It received 90 votes in the Senate, an overwhelming show of support that essentially forced the president to sign it — despite the vocal opposition of Vice President Dick Cheney , who wanted to exempt the Central Intelligence Agency.

“All my career, I have supported the rights and prerogatives of the commander in chief. We need a strong president, and in wartime this is more important than ever,” McCain said during the floor debate. But to make sure the United States never tortures its prisoners, he said, “we are duty bound to take action.”

The torture ban, however, also prompted one of Bush’s most widely publicized signing statements, in which he declared that he would interpret the ban “in a manner consistent with the constitutional authority of the president to supervise the unitary executive branch and as commander in chief.”

It read like a hint that Bush might simply ignore the law. McCain and Republican John W. Warner of Virginia, then the chairman of the Senate Armed Services Committee, warned that the panel “intends through strict oversight to monitor the administration’s implementation of the new law.”

McCain has also challenged the Bush administration through his investigations. Congressional oversight experts praised his 2005 efforts, as chairman of the Indian Affairs Committee, to uncover details of lobbyist Jack Abramoff’s schemes to defraud American Indian tribes. The investigation helped document Abramoff’s activities and sent two administration officials to prison for lying to the committee about their involvement in the scandal.

McCain also pushed the Defense Department aggressively in 2004 for documents about an Air Force plan to lease tankers from the Boeing Co., which McCain called expensive and unnecessary. The controversy forced the Pentagon to withdraw the nomination of Air Force Secretary James G. Roche, who supported the deal, to become secretary of the Army.

In other areas, though, McCain has voted regularly for measures to strengthen the executive branch. He supported last year’s law authorizing military tribunals for those held in military custody and suspects of terrorist ties — after securing language to make sure the administration would abide by the Geneva Conventions. He shrugged off criticism that the law allows very limited court review of the tribunals’ work.

During the Clinton administration, McCain cosponsored a resolution of support for the deployment of troops to Bosnia, and he tried to get the Senate to authorize Clinton to send ground troops to Kosovo, though the president had not asked Congress to authorize either one. “This is a role for the Congress of the United States to play, endorsing the president’s ability to use whatever force is necessary in order to bring the conflict to a conclusion,” McCain said during the Kosovo debate. The resolution failed.