Some call them "the unreliables" — huge numbers of prospective voters who favor one party or the other but have a spotty record of actually showing up at the polls.

Six weeks before Election Day, both parties are mounting an unprecedented effort to get these highly prized people to cast their ballots — not on Nov. 2 but as far in advance as possible, in some cases this week.

In Arizona, singer Linda Ronstadt (search) urges people at a rally to vote early. In Ohio, volunteers deliver an absentee request form to a homebound 85-year-old woman. In Iowa, Democrats train thousands of volunteer couriers to pick up early ballots from voters.

With 32 states now offering some form of early voting, the tradition of mounting a massive get-out-the-vote drive in the week before the election has given way to a sustained six-week chase as balloting in one state after another opens for business. In a sense, it's like the movie "Groundhog Day," requiring the campaigns to treat every day like Election Day for more than a month.

For example, Democrat John Kerry's trip to Iowa this week was keyed to the start of early voting there on Thursday.

Iowa is a good state to illustrate the importance of the effort: In 2000, George Bush won a majority of the ballots cast on Election Day — but he lost the state to Al Gore, who had greater support among early voters.

Both Iowa and Maine, two battleground states where any registered voter can cast an early ballot, begin mailing out absentees and welcoming walk-in voters this week.

With plenty of prodding from the Bush and Kerry camps, more than 100,000 Iowa voters already have submitted absentee request forms. Some of those were turned in as far back as January, when participants in party caucuses were a captive audience for officials preaching the benefits of early voting.

President Bush, for his part, last week sent out a widely distributed e-mail in which he told voters: "If you're going to be busy on Nov. 2, I encourage you to take this opportunity and vote early."

That rankled Democrats in Missouri, where being "busy" isn't a legal reason to vote absentee.

Kerry's Web site, meanwhile, tells voters: "You don't even have to be out of town on Election Day to vote absentee."

There are implications for the campaigns that extend far beyond the mechanics of getting out the vote, from the timing of ads to travel to budgeting. But don't ask the parties to reveal specifics of their competing battle plans.

"Why would I?" asks Karen Hicks, field director for the Democratic National Committee.

"It's kind of a trade secret," says Bob Fannin, state Republican chair in Arizona, where both parties say close to 60 percent of ballots could be cast early.

Details aside, it all comes down to a combination of high-tech organization and old-fashioned shoe leather, tailored to the different ground rules in every state.

In West Virginia, Oct. 13 is the last day to register to vote and the first day for early in-person voting. Both parties have talked about using that day to register new voters and then immediately turn them around to cast ballots, says Robert Rupp, a political scientist at West Virginia Wesleyan College.

"We have come a long way from getting absentee voters in nursing homes," Rupp said.

In many target states the general strategy is the same: to identify unreliable votes and get them to request early ballots. The parties then can determine from election officials which voters have returned those ballots — and which should be prodded.

"You have to chase 'em to turn in their application, and then chase down their ballot," says Jim Pederson, Democratic Party chairman in Arizona.

Jodee Winterhof, political director for America Coming Together, an anti-Bush group making a push to round up early voters in battleground states, said her group could end up contacting some voters five times or more to make sure they cast early ballots.

While it's nice to lock in an early ballot from someone who votes regularly, she said, "it's more helpful to get voters who don't vote regularly or who are newly registered."

Such voters are also referred to as infrequent voters, low-efficacy voters and sporadic voters.

"In 40 years, I have never seen anything close to this effort," says the GOP's Fannin in Arizona. He says the national party is keeping close tabs: "We've been monitored every week for well over a year as to what our results are."

Each side can claim at least some bragging rights.

In Iowa's largest county, the Polk County auditor reported that by the start of September, there had been 12,150 requests for absentee ballots from Democrats, 1,364 from Republicans and 3,087 from voters not registered with a party.

In Pennsylvania, meanwhile, an ABC News poll found that 21 percent of voters said they had been personally contacted by the Bush campaign, compared with 14 percent who said they had been contacted by the Kerry camp.