Incumbent Republican Deborah Pryce leads Democrat Mary Jo Kilroy by 3,536 votes. But there are more than 10,000 provisional ballots left to be counted, and the Columbus Dispatch reports the Kilroy campaign is still hard at work:

Kilroy's campaign called about 70,000 voters last weekend and aired television and radio ads asking people who cast provisional ballots to contact the campaign and county boards of elections to make sure their votes in the 15 th Congressional District are counted.

According to the article, "95 percent of people who voted provisionally in Franklin County were able to provide a Social Security card or driver's license number that can be used to establish residency." If you assume 95% of provisional ballots end up being verified and counted, a down and dirty sketch of the math shows that Kilroy would have to win 70% of them to flip the seat. Furthermore, if the addition of the provisional ballots brings Kilroy within 998 votes of Pryce (either ahead or behind) - it will trigger a mandatory recount in all three counties.