(CNN) -- Why does Ohio matter?
When it comes to deciding the presidential race, you have probably heard the oft-mentioned narrative: No Republican candidate in recent memory has claimed victory without first winning the Buckeye State. And a diverse state like Ohio, with 18 electoral votes, has long been evenly split between the two parties.
Now add another chapter to the potential drama -- provisional ballots in Ohio that will not be counted until November 17. And yes, the scenario is not far-fetched: If the presidential vote difference in Ohio is razor thin, then absentee, mail-in, and especially provisional votes could delay a final total for perhaps 10 days.
Even then, the nation may still have to wait longer. If vote totals still remain close, an official recount in Ohio could be ordered or one or more candidates -- or a political party -- could challenge the outcome in court.
Why a 10-day wait? By law, local election boards in Ohio are given up to 10 days to determine provisional ballot eligibility.
Officials want to make sure there is no double-dipping -- so that those who vote early by mail do not then show up on Election Day in person and try to vote again. Discrepancies, such as checking recent address or name changes, could complicate a process, where every vote is considered in play.
The fight in Florida in 2000 was all about how disputed ballots should be counted -- and whether uniform standards established by a legislature were being applied fairly statewide. That may be the key issue in Ohio this time if there is controversy over why and how many provisional ballots are being discarded.
Ohio has had many of its Republican-led legislative efforts thwarted in recent weeks.
Federal and state courts have expanded early voting to everyone in the crucial last days before Tuesday's election. Original legislation would have only allowed military members and their families to vote in person in the three days before Tuesday. Judges found that violated "equal protection" guarantees.
And courts have ordered the state to preserve the provisional votes of those who may have cast them in error because of poll worker misinformation -- such as sending someone to the wrong polling place.
The state has among the highest provisional ballot rates in the United States -- an estimated 200,000 or more were cast in Ohio four years ago. About 40,000 were later declared ineligible.
Ohio officials promise voters will get a fair, transparent election process and that their ballots will be counted.
"It's important for folks to know we're in Day 33 of voting," Ohio Secretary of State Jon Husted told CNN's Don Lemon about the early voting process. "It's gone smoothly here in Ohio. The rules are fair and consistent for everyone."
But state Democrats as well as labor unions and left-leaning groups have challenged the regulations. Two federal lawsuits are pending over the provisional ballots, and the electronic software the state is using to coordinate the vote totals in the counties. Those groups claim Ohio voters are being disenfranchised.
State election officials told CNN on Monday that 1.6 million voters in Ohio have cast early ballots. Of those, more than 1.1 million voted by mail and nearly 500,000 in person, said Matt McClellan, a spokesman for the Secretary of State in Ohio.
This year for the first time, Ohio mailed absentee ballot applications -- one for every registered voter there. More than 85 percent have been returned.
Overall, more than 5.6 million ballots were cast in Ohio in the 2008 presidential election. Barack Obama won the state by 4.6 percent, or just over 262,000 votes. A similar number voted in 2004 when George W. Bush took Ohio by a less comfortable margin of 2.1 percent or 118,000 votes.
There has been a public expectation that courts would be the ultimate arbiters of any voting dispute, especially those in a post-election environment. When federal courts recently ruled against state efforts to limit access to early voting, and by doing so used unusual legal reasoning.
"These two rulings in Ohio could give Obama the edge," said election law expert Rick Hasen. "What the Republican [state] legislatures have taken away, the federal courts, including some Republican judges, have restored, relying in part on the arguments conservative justices endorsed in Bush v. Gore.
That 2000 blockbuster relied on "equal protection" guarantees to dismiss Florida's ballot-counting procedures. It was a rare federal and judicial intervention into broad election administration, a duty the Constitution essentially bestows on the states.
The super lawyer who successfully argued that high court case for Bush that year has a message for those anticipating a long, litigated road to the White House:
"If you follow the rules that were in place on Election Day with respect to counting the ballots then the presumptive outcome will be respected when the Electoral College votes are counted."
CNN Senior Producer Carol Cratty contributed to this report.