John McCain has been called a "maverick" Republican for so long that most Americans started taking his independence for granted a long time ago.

His public persona as a straight-talking, pork-busting, politically centrist war hero — established during his 2000 presidential run — is one of the presumptive GOP nominee's greatest assets.

But a look back at McCain's more than 25-year political career reveals a figure far more complicated.

He has demonstrated a repeated willingness to stray from GOP orthodoxy since he first ran for Congress in 1982. He also has a record of heartily supporting Bush on some of his most controversial priorities, including the Iraq war and comprehensive immigration reform. In 2007, McCain voted with Bush 95 percent of the time, at least when he was there.

Being a maverick has political value. Presidential candidates rarely present themselves as strict party people. And the notion of rugged individualism is still ingrained in the American psyche.

HARD TO DEFINE

Still, a maverick is sometimes hard to define and, in politics, the free spirits are often the most inconsistent.

Over the years, McCain has given the opposition ammunition: The Democratic National Committee issues regular "McCain Myth Buster" news releases accusing McCain of "walking in lockstep with President Bush." New books such as "Free Ride: John McCain and the Media" by liberal writers David Brock and Paul Waldman attack the "maverick" characterization as, to put it mildly, a dramatic media exaggeration.

McCain campaign insiders don't seem worried.

"It's a natural thing for the Democrats to go right at the McCain brand, his independence and reputation for doing what he thinks is right, regardless of his political interest or self-interest," said Charlie Black, a senior McCain campaign adviser.

A March 21 memo from Rick Davis, McCain's campaign manager, referenced a recent Gallup Poll that found McCain earning a better favorable rating from Democrats and left-leaning independents than Democrats Barack Obama and Hillary Clinton get from Republicans and right-leaning independents.

McCain has bucked the party line often enough to be able to lay claim to the "maverick" moniker, even if his overall record is more complex.

In 2001, the Arizona senator was one of two Republicans to vote against Bush's signature tax-relief program.

The other was then-Sen. Lincoln Chafee, R-R.I., one of the Senate's most unabashedly liberal GOP members. But today, McCain supports making the tax cuts permanent because letting them lapse is tantamount to a tax increase.

He is eager to work with Capitol Hill Democrats on topics such as immigration and climate change, but has a history of clashing heatedly with Senate colleagues in both parties.

In February 2000, he delivered a critique of religious conservative leadership, which included blasting Jerry Falwell and Pat Robertson as "agents of intolerance." Yet in 2006, he delivered the commencement address at Falwell's Liberty University.

A TRUE 'MAVERICK'?

So is McCain truly a "maverick"?

"It's part of who he is, but that's not him in his entirety," said Dan Schnur, who was communications director for McCain's 2000 presidential campaign but is not affiliated with his current bid.

McCain recently quipped that he prefers the term "Great American" to the over-worn "maverick" label.

"When you look at my great hero, (progressive GOP President) Theodore Roosevelt, I think many viewed him in those days as not a stereotype Republican," McCain said. "So I don't know if you would call it a 'maverick,' but I certainly have issues that I think can attract independents."

Matt Welch is the editor in chief of the libertarian magazine Reason and the author of a critical look at the senator from Arizona titled "McCain: The Myth of a Maverick." Welch acknowledged that McCain, who spent more than five years as a prisoner of war in Vietnam, has demonstrated "maverick-y" behavior ever since he was "the class pop-off" and "a funny kind of punk kid who was getting in fights."

McCain's military background has a lot to do with any independent tendencies. Unlike many Republican leaders and activists, McCain did not rise from the conservative movement. In fact, many of the patriotic values that McCain espouses from the campaign stump are nonpartisan, such as duty, honor, courage and service.