Tens of thousands of voter registration applications, some dating back at least a year, are caught in a backlog and have yet to be processed due to an error by the Texas Department of Public Safety, the leader of an association of county election officials said Wednesday.

Texas Democrats, who are fiercely contesting key offices in closely watched races this year, are calling on Gov. Greg Abbott, a Republican, to investigate the problem, which was first reported by Votebeat.

Some voter registration applications and updates submitted through DPS’s online driver’s license portal were never sent to county voter registrars, the state told county election officials.

In an emailed statement Wednesday, DPS said “the system issue has been resolved” and the agency worked with the secretary of state’s office “to identify incomplete records to backfill incomplete information.”