HURRY UP AND WAIT. It's safe to assume just about anyone with even a passing interest in politics is anxious to see what happens today, but it's worth taking a moment to remember that, in some of the very close races, it's possible we may not know the results tonight, or even tomorrow.

[E]lection experts warn that the number of voters forced to cast provisional ballots Tuesday because of eligibility questions could delay some results in tight races for days or weeks.

New statewide voter databases, strict ID requirements and other factors may increase the percentage of voters whose paper ballots must be reviewed by local officials.

If there's a question about a voter's eligibility, he or she will still be able to cast what's called a "provisional ballot," the validity of which will be determined after other votes have been tallied. It's likely to come up with a voter goes to the wrong precinct, lacks required ID, is listed by a slightly different name than appears in state databases, etc. (In 2004, the first year were used nationwide, about 1.9 million people cast provisional ballots. About 1.2 million were accepted.)

"I think we're going to see a lot more provisionals than we've seen before," says Kimball Brace, president of Election Data Services. "For a poll worker, a provisional is the easy way out."

As USA Today recently noted, "Some states allow extended periods for determining the eligibility of provisional voters -- up to 28 days in California. In Washington state in 2004, provisional ballots played a role in delaying Gov. Christine Gregoire's victory for more than eight weeks."

"With so much attention focused on pre-election barriers, we've almost forgotten about things that could cause problems on and after Election Day," said Dan Tokaji, a professor at Ohio State's Moritz College of Law. "Provisional ballots are at the top of that list."

In some instances, states may not even know how many provisional ballots were cast until after today.

--Steve Benen