Tens of thousands of Americans will vote in November using a special kind of ballot that must be counted by hand, potentially leaving the outcome of the presidential election in doubt as elections officials argue over each vote.

Sound familiar?

Although it might stir memories of hanging and pregnant chads from the 2000 election, the "provisional ballot" is a new national voting requirement meant to ensure no voter is turned away. For the first time, provisional ballots will be available at precincts nationwide for those who can't find their names listed at the polls.

Yet, just three months before what looks to be another extremely close presidential election, states don't agree about how to count these ballots. Some localities are worried they won't have time to tally them, and voting rights advocates fear many won't be counted at all.

"They do have the potential to be the chad of 2004," said Doug Chapin, director of the Election Reform Information Project (search), a nonpartisan group that studies elections. "Given that you have to basically ascertain the validity of a ballot, ballot by ballot, you open yourself up to the same kind of high-stakes politicization of the process we saw in Florida in 2000."

The Help America Vote Act of 2002 mandated provisional ballots. The idea was to prevent properly registered voters from being turned away from the polls because of clerical errors with registration lists or other problems. Civil rights groups estimate that happened to 1.5 million or more voters in 2000.

Under the new law, anyone who claims to be registered in the jurisdiction where they try to vote but whose name is not listed must be given a provisional ballot. If the voter's registration information is verified later, the ballot is included in the total for the election.

No one knows how many provisional ballots will be cast in November, in part because only about half the states allowed such ballots or something similar in 2000. It will easily be tens of thousands nationwide. In Los Angeles County alone, 44,000 were cast in the March primary.

But verifying voter eligibility and hand-counting the ballots takes a long time. Some states, by law, give counties just days to finish. That has election administrators contemplating a nightmare scenario: What happens if the number of provisional ballots is bigger than the apparent margin of victory on Election Day? The outcome could hang in doubt while election officials rush to beat the clock.

"It would be like Florida in 2000, basically," said Thomas Leach, spokesman for the elections board in Chicago, where voters cast 5,914 provisional ballots in the March primary.

"We've talked about this all year, the fact that there could be a big delay in the counting of these and the determination of who the victor was," Leach said. "It was a task just going through the 5,914 applications. ... If you've got 50,000, it can overwhelm you."

Election officials say it could happen. In fact, it already has.

In a Utah city council primary last year, the outcome hinged on 31 provisional ballots.

Kansas has used provisional ballots since 1975. "Every election cycle, there is a race somewhere in the state of Kansas decided by provisional ballots," said Secretary of State Ron Thornburgh.

Adding to the potential for confusion, states differ over how and when provisional ballots are counted.

Some, like California, New Mexico and Pennsylvania, count at least the statewide and national races on provisional ballots cast in the wrong locality. Others, including Florida, Illinois and Indiana, don't count a provisional ballot at all unless the voter is in the right precinct.

"That is the problem with provisional balloting under the Help America Vote Act," said Maria Valdez, midwest regional counsel for the Mexican American Legal Defense and Educational Fund, which is considering a lawsuit on the grounds that voters aren't treated equally.

"It really could look like it's trying to open access, but because it is based on a state-by-state determination, it really could restrict access," Valdez said.

Valdez and other activists cite Chicago's primary. Of the 5,914 provisional ballots cast, only 416 were ever counted. A total of 1,294 came from voters in the wrong precinct, 2,461 from voters who didn't fill out an affidavit properly and 1,461 from people who could not be verified as registered voters, according to Chicago's elections board.

Another factor is time. In Illinois, officials have 14 days to tally provisional ballots, while in California it's 28 days. Florida and Georgia give elections officials just two days, raising the possibility of another court battle if time is running out and ballots that could tip the election remain uncounted.

Some Florida elections officials are confident they'll be able to validate and count any provisional ballots within the allotted time, but others aren't so sure.

"It's an incredible problem," said Ion Sancho, supervisor of elections in Leon County, Fla. "But that's what the legislature told us to deal with, so that's what we deal with."