McCain is a longtime opponent of so-called earmarked projects while Obama and Clinton have always asked for their share. Now that critics of Congress' pork barrel ways are intensifying their election-year attacks, Obama and Clinton have jumped on the bandwagon.
Old-timers in both parties led the Senate to beat back the ban. McCain couldn't attract even a majority of Senate Republicans to vote with him Thursday night behind the earmark moratorium touted by party conservatives as a way to restore the GOP's credibility with voters. Only three Democrats joined with Clinton and Obama in voting for it.
The measure failed on a 71-29 vote. Supporters needed 60 votes to win.
The foot soldiers in this week's push to abolish pork-barrel politics - a campaign whose most prominent champion is John McCain - were two rookie Republican senators whose scrappy tactics have drawn the ire of lawmakers in both parties.
Tom Coburn of Oklahoma and Jim DeMint of South Carolina, both conservative transplants from the House, have stalled and stymied their way to notoriety over the past two years by going after home-state projects, known as "earmarks," that other senators try to slip into legislation.
Written off at first as pesky annoyances by colleagues who prize seniority and consensus, Coburn and DeMint managed to bring increased attention to their cause, especially after Democratic presidential hopefuls Barack Obama and Hillary Rodham Clinton picked up the call.
The anti-earmark campaign culminated Thursday when senators had to vote on banning the practice for a year, putting some senators in a tight political spot.
Along the way, Coburn and DeMint were scorned and threatened by Democrats and Republicans alike. They are held in disdain by party leaders whose carefully laid plans are often upended by their efforts, and by senior senators who have spent decades mastering the art of steering federal dollars to their states.
"I don't intend to irritate anybody," Coburn said in an interview. "I've just chosen to say, 'I'll take their consternation, if that's what it takes."'
Sen. Ted Stevens, R-Alaska, once said their efforts would succeed over his dead body - "I will be taken out of here on a stretcher," he snarled.
Sen. Patty Murray, D-Wash., warned she would retaliate. "What is good for the goose is good for the gander. ...Your project may be next."
In Maine, Republican Sen. Susan Collins and Democratic Rep. Michael Michaud said they would oppose the ban on earmarks.
Coburn and DeMint are routinely accused of wasting the Senate's time with scores of amendments that stand virtually no chance of approval and procedural tactics aimed at blocking what they consider to be bloated legislation.
"Ridiculous," Sen. Dick Durbin, D-Ill., said this week of their anti-earmark tactics.
DeMint describes the response to his efforts as "cold but civil."
"I was just told when we started this, 'You're going to make a lot of people mad, you'll never be in leadership, you're going to marginalize yourself,"' he said.
All of that and more has happened, he said, but it hasn't dampened the duo's determination.
McCain has long railed against wasteful spending and was often a lone voice of opposition to the scores of earmarks stuffed into must-pass annual funding bills. Lawmakers had come to expect the Arizonan's perennial rants against the practice. But his amendments to erase the projects from legislation almost always failed.
With McCain on the campaign trail, Coburn and DeMint - veterans of the more bare-knuckled House who came to the Senate in 2005 - took a far more in-your-face approach. They've insisted on votes and voiced action-blocking objections in their one- or two-man stands on the Senate floor to protest what they consider wasteful spending and call attention to the lawmakers who request it.
Coburn, an obstetrician by training, claims he has saved taxpayers $1.7 billion through his efforts, which included eliminating $1 million for a museum dedicated to the Woodstock Festival, known to its opponents as the "hippie museum."
Most of the time, though, it's a losing battle. Senators jealously guard their spending prerogatives. Most abide by an unspoken code against scrutinizing colleagues' projects, lest their own become targets.
"No one wants to unilaterally disarm," said Leslie K. Paige of Citizens Against Government Waste, a spending watchdog group.
Coburn incurred Stevens' wrath in 2005 when he tried to strip $452 million for two Alaska bridges - one known as the "Bridge to Nowhere." Stevens handily won that skirmish in an 82-15 vote after his tirade, but he eventually lost the bridges anyway.
"My votes have never been designed to win. They've been designed to inform the American public about what really goes on up here," Coburn said. "The American people have awakened, and there's a rumble, and (lawmakers are) hearing about it."
DeMint, a confessed "recovering earmarker," came to the cause later. He once bought the argument that earmarks were the only way to bring federal money back to his district. He soured on them after seeing most of them going to senior lawmakers and leaders who used the goodies as sweeteners to draw votes for unrelated measures.
When Republicans were clobbered in the 2006 elections, DeMint concluded that violating the Senate's norms of courtesy by attacking individual projects was the only way to grab his colleagues' attention.
"It's time to go after this any way I can. We'll blow the place up if we have to to get this done," he said.
He tasted his first victory a year ago, winning an amendment to an Iraq war spending bill to deny spinach growers $25 million in disaster relief.
While most concede that earmarks have gotten out of hand, many lawmakers defend the practice as a legitimate exercise of Congress' power of the purse. Still, with a spotlight now shining, some lawmakers are tempering their criticism of DeMint and Coburn.
"I haven't seen any proposal by any of them that I think is good," said Sen. Pete V. Domenici, R-N.M. But he added: "I'm not mad at anybody. In good faith, they're worried about earmarks."
Asked about their tactics this week, Stevens sniffed: "It's a free country. That's their right."