Independents (and even a few Republicans) won’t pick the Democratic Party’s nominee in 2004, but they could well determine who’ll survive some key early tests and will have an opportunity to carry the party’s banner.

If that sounds outlandish, you don’t have to take my word for it. Just consider what campaign consultant John Weaver told me earlier this week.

[IMGCAP(1)] “Independents will probably end somebody’s campaign in New Hampshire and South Carolina, and they may jump-start someone else’s campaign,” said Weaver, a Republican-turned-Democrat who was Arizona Sen. John McCain’s (R) top strategist during his 2000 presidential bid.

With a crowded Democratic presidential field taking shape, and the Democratic electorate likely fractured among a number of hopefuls, independent voters look to be a key swing group in early primary states, such as New Hampshire (where undeclared voters can vote) and South Carolina (which has no party registration).

They’ve been important before.

Three years ago, McCain threw a scare into George W. Bush in the race for the GOP presidential nomination when he clobbered the Texan 49 percent to 30 percent in New Hampshire, winning registered Republicans by just 6 points (44 percent to 38 percent), but getting 61 percent of independents.

On the Democratic side, former Sen. Bill Bradley (N.J.) almost did the same thing in the Granite State to his party’s favorite, then-Vice President Al Gore. Bradley lost to Gore by just 4 points, and he almost certainly would have defeated the sitting vice president if McCain had not been pulling independent voters into the GOP primary.

Incredibly, McCain drew 3,320 write-ins in the Democratic primary — more than half of Gore’s margin over Bradley.

McCain also carried Michigan’s open primary (51 percent to 43 percent) even though Bush won 66 percent of Republicans voting in the GOP primary. But Republicans constituted only 48 percent of voters in the primary. Two-thirds of independents, who constituted 35 percent of the GOP primary electorate, went for McCain, and 83 percent of registered Democrats (who accounted for 17 percent of the electorate) cast their ballots for the Senator.

Yes, Michigan Democrats are more likely to have a closed caucus instead of a primary next year, but the important point is that open primaries are unpredictable events.

Some of McCain’s remarkable appeal among independents came from his personal story. He is, after all, a hero. But his straight-talking style and calls for reform (especially for campaign finance reform) also resonated with independents, who are less concerned with ideology than strong partisanship.

Bradley lacked McCain’s remarkable personal story, but the former New Jersey Senator appealed to independents because he positioned himself as an untraditional politician who would take on the special interests (even in his own party) and wouldn’t rely on easy, ineffective answers to important questions facing the nation.

“Independents are looking for authenticity,” says Weaver, and both McCain and Bradley conveyed a sense that they were honest and forthright, not creatures of their consultants.

Not surprisingly, allies of each of the presidential hopefuls are trying to figure out how to take advantage of a modified McCain/Bradley electoral strategy that woos independents who are eligible to participate in open primaries.

The two candidates who would seem most likely to try to score among independents are former Vermont Gov. Howard Dean and Connecticut Sen. Joe Lieberman.

Without any connection to Washington, Dean can run as a pure outsider who isn’t a prisoner to special interests on Capitol Hill. He’s spunky, like McCain, and he has a quirky issue mix (he supports gun owners’ rights and has balanced budgets, but signed civil-unions legislation, though without fanfare) that might allow him to appeal to Bradley or even McCain voters.

Lieberman may have trouble appealing to the most liberal constituencies in the party, and that may well force him to target independents, who might like his reputation for integrity and his ideologically mixed message.

North Carolina Sen. John Edwards, who has already tried to position himself as a Washington outsider and a fighter, may also seek to claim a chunk of independents, who often like a fresh face. And while Florida Sen. Bob Graham is still mulling his options, some Democratic strategists believe that he could also be appealing to independents.

The potential importance of independent voters is demonstrated by the eagerness of allies of presidential hopefuls Rep. Richard Gephardt (Mo.) and Sen. John Kerry (Mass.) to portray those long-time politicians as contenders for McCain’s and Bradley’s supporters in New Hampshire.

For supporters of Gephardt, their man’s record on campaign finance reform (and other proposals in the works) will resonate with independents. And according to one Kerry backer, it’s a no-brainer why Bradley and McCain voters could be attracted to the Massachusetts Democrat: “Bradley voters were policy-centric, and they’ll be looking for some heft on the policy front.” Like McCain, Kerry has a strong Vietnam War record, and that gives him a good personal story to tell.

As the Democratic race develops, keep your eye on what core Democratic groups do. But don’t forget those unpredictable independents. They are going to have an impact.