A rabble-rouser from his earliest days, John McCain has never been one who likes to be told "no." There's no reason to think a President McCain would be any different.

McCain styles himself as a Teddy Roosevelt Republican, eager to be in the arena. If elected, he could be expected to pick certain issues and push them to the limit. Look for him to throw down the gauntlet in a few high-profile battles — vetoing legislation larded with pork-barrel projects, for example.

He's already promised to make an example of legislators who try to finagle government dollars for pet projects without thorough review, saying over and over, "You will know their names. I will make them famous."

He'd plant his feet firmly in resisting a timetable for withdrawal from Iraq. He'd try to give people new tax credits for health insurance and — in a first for a Republican president — move to deal aggressively with global warming even while opening more offshore waters to oil drilling.

But his my-way-or-the-highway approach would only take him so far, particularly when the nation's economic crisis is sure to limit maneuvering room for whoever becomes the nation's 44th president. And especially for McCain, since Democrats are likely to strengthen their majorities in the House and Senate come Election Day.

As a candidate, McCain has stressed his ability to work with congressional Democrats while standing up to those in his own party. There's no skill he'd need more if elected.

"He's going to have to truly be the maverick McCain who takes on his own party," said Darrell West, director of governance studies at the Brookings Institution, a think tank. "He will not be able to govern as a conservative Republican."

McCain's task would be further complicated by the conservative stances he adopted during the campaign season.

"If he compromises too much with the Democrats, he'll face a grass-roots rebellion from conservative activists who were always suspicious that McCain is not one of them," West said.

HIGH EXPECTATIONS

McCain talks boldly about what he could accomplish if voters put him to work at the Resolute Desk in the Oval Office.

Even in the face of the economic meltdown, he has continued to set high expectations.

Strengthening Social Security? "Look, it's not that hard to fix Social Security. It's just tough decisions."

Finding Osama bin Laden? "I'll get him no matter what, and I know how to do it."

Financial chaos? "The point is we can fix our economy."

What about the triple challenges of healthcare, energy policy and entitlement reforms? "We can do them all at once."

In short, he says, "We need to change the way government does almost everything."

McCain's good friend Sen. Lindsey Graham, R-S.C., envisions McCain using the presidency in a big way. "Man, would we do a lot if he got to be president," Graham says. "He would push Congress to do things it should've done 20 years ago."

This is how McCain framed his mission when he announced his candidacy on April 25, 2007, in Portsmouth, N.H.:

"I'm not running for president to be somebody, but to do something; to do the hard but necessary things, not the easy and needless things."

For all that bullish talk, though, McCain knows he will have to display a measure of pragmatism.

Three times in recent weeks, for example, he has supported legislation allowing thousands of pork-barrel projects to go forward, rather than oppose bills that contained other important features such as the $700 billion financial rescue package.

FINANCIAL CRISIS FACTOR

And although neither candidate wants to talk about it, the financial crisis surely will narrow the next president's possibilities.

"This financial crisis may just have pulled the rug out from under any meaningful honeymoon, when a president tries to identify his top priorities and exploit the honeymoon period," said Steven Smith, a political science professor at Washington University in St. Louis. Instead, Smith said, "A major part of the next president's first State of the Union address will be how we proceed after getting through the first stages of this crisis. ... There are going to be pretty massive restraints on new initiatives."

Even McCain's promises to cut government spending would be tougher to fulfill because of the economic mess, Smith said, because "it doesn't make a lot of sense economically, when we might be headed into a recession, to radically reduce the federal deficit."

McCain himself has acknowledged that the economy is not his strong suit, meaning he'd have to rely heavily on his staff and Cabinet.

McCain is more comfortable dealing with foreign policy than domestic affairs, and he'd have a freer hand there. The former Vietnam prisoner of war and son and grandson of admirals eagerly claims the credentials to serve as commander in chief. He refuses to set a timetable for withdrawing U.S. troops from Iraq, and pledges unspecified troop increases in Afghanistan.

For all his years in the public eye, the 72-year-old McCain, a four-term senator, has had little in the way of executive experience, making it harder to predict his governing style.