With the U.S. Senate recount still incomplete, attorneys on both sides have already armored up for the next pitched battle: over whether to reexamine thousands of rejected absentee ballots.

With Republican U.S. Sen. Norm Coleman clinging to a reed-thin lead over DFL challenger Al Franken -- 180 votes as of Saturday night -- the issue of how and when absentee ballots should be counted has election law experts everywhere closely tracking the Minnesota recount drama.

In a race this tight, the difference could come down to clerical errors on absentee ballots or even a challenge of Minnesota's law governing such ballots.

"Campaigns over the years have challenged anything and everything," said recount expert Timothy Downs, principal author of "The Recount Primer" who has been involved in most major recounts over the years, including the biggest: Gore vs. Bush in 2000. Downs' co-author, Chris Sautter, hit the ground in Minneapolis last week as part of Franken's recount team.

On Wednesday, both sides will face off at a state Canvassing Board hearing that could prove momentous, with discussion and perhaps a ruling on whether rejected absentee ballots are in or out.

Despite the mounting number of challenges being made to the regular ballots being recounted now -- more than 1,900 as of Saturday evening, almost evenly divided between the campaigns -- experts say that most of those disputes will be easily resolved by the five-member board. As a result, the challenges may in the end make only modest changes.

But if the Canvassing Board decides to review rejected absentee ballots, many still unexamined votes could get thrown into the mix, adding far more uncertainty.

"Ultimately, if the number of rejected ballots start to make a large enough stack, it can cast some cloud over the regularly recounted ballots," said Edward Foley, who directs the election law center at Ohio State University's Mortiz Law College. Foley said the race has already taken enough twists and turns to merit its own chapter in his upcoming book on the history of disputed elections.

A Star Tribune analysis of rejected absentee ballot lists collected from 25 of the state's 87 counties shows that 2,066 would-be absentee voters were excluded from initial vote tallies in just those counties. The total does not include Hennepin County, home to about one quarter of the state's population, or several other metro counties.

More ballots, more errors

The reasons for rejecting absentee ballots vary. Many voters failed to fill out voter registration cards or to sign the backs of absentee envelopes, as required by law. Those ballots, Downs and others say, could be dispensed with quickly at a review hearing.

But other situations could require careful scrutiny. And the sheer volume of absentee ballots this year has changed the conventional wisdom on what role they could play.

More than 288,000 Minnesotans cast absentee ballots this year -- nearly one voter in 10 -- essentially turning the state's absentee system into a type of early voting.

Once an alternative for the infirm, affluent snowbirds and travelers, absentee balloting this year became a key element of Democratic voter turnout strategy.

"We had lines out the door for absentee voting," said Ramsey County Elections Manager Joe Mansky. "The lines had blacks, whites, Hispanics, immigrants, young, old -- everything," Mansky said.

With increased numbers come increased errors, both by voters and administrators, said elections expert Robert Stein, a political science professor at Rice University, in Texas. Stein's class on elections and voting behavior spent Friday monitoring Minnesota news sites, examining every twist and turn of a race that has given election junkies one last rush.

"I don't mean to be disrespectful," Stein said, "but it's been a hoot to watch. Everybody thought this was the kind of thing that would happen in Florida or Texas."

In Washington state's protracted 2004 gubernatorial race, a hand recount found 561 administrative errors on what had been rejected absentee ballots in a contest where the winner had led by 129 votes at one point.

"You're down to less than two thousandths of a percent difference," Stein said on Friday, when fewer than 150 votes separated Coleman from Franken. "That's infinitesimal."

Board vs. court

The vast majority of rejected votes will stay rejected even on close examination, Downs said. "But in a race that could come down to a handful of votes, if even a fraction are found eligible, that could affect the outcome."

Downs cautioned that no one should be too sure who it would favor. "There is no profile of an absentee voter that holds up anymore," he said. "It used to tilt Republican, but it's changing so much it's not predictive."

The Franken campaign has argued vigorously that rejected ballots should be reexamined immediately by the Canvassing Board, going so far as to present affidavits from voters whose absentee ballots weren't counted.

Coleman recount attorney Fritz Knaak said the Coleman campaign is basing its objection on the fact that the current recount is an administrative process rather than a judicial one. An administrative recount, he said, echoing an opinion issued by the attorney general last week, is designed under Minnesota law to reexamine ballots already counted, not to scrutinize decisions made about the eligibility of voters or validity of ballots. Those questions, Knaak said, would properly be considered by a court in an election contest brought by voters or campaigns.

But Raleigh Levine, an election law professor at William Mitchell College of Law, said boards elsewhere have decided otherwise.

"There definitely are other jurisdictions in which defective absentee ballots are examined by the canvassing board," Levine said. In Massachusetts, she noted, registrars are instructed to reexamine rejected absentee ballots as part of the administrative recount.

Stein, of Rice University, said that ultimately, Minnesota's contest is unlikely to be determined by anything as mundane as an administrative recount.

"The short answer is someone is going to win the election and the other guy is going to go to court," he said.

News researcher Roberta Hovde contributed to this report. plopez@startribune.com • 651-222-1288 vonste@startribune.com • 612-673-7184