IOWA CITY, Iowa (AP) — A Republican candidate seeking to flip a Democratic-held congressional seat in Iowa has pulled ahead by 50 votes after a county discovered that that it had failed to report a small town’s votes. The dramatic turn was the latest in the seesawing race between Republican Mariannette Miller-Meeks and Democrat Rita Hart. And it may not be the last.

The 24 counties in the southeastern Iowa district were certifying their votes Tuesday after completing their official canvasses. It’s possible additional provisional ballots or absentee ballots that arrived by Monday at noon could be added to some county totals. The race is considered among the closest in the nation and could remain unsettled for weeks.