O’FALLON, Mo. (AP) — Missouri Secretary of State Jay Ashcroft is investigating why a suburban St. Louis polling place opened 90 minutes late for this month’s primary election.

Ashcroft said Monday that doors at the polling place in O’Fallon remained locked 90 minutes past opening time for the Aug. 7 election. He says the problem could have impacted both the Republican and Democratic races in Missouri House District 102. Both were decided by less than half of 1 percent of the vote.

Ashcroft’s office says the St. Charles County Election Authority first blamed a malfunction due to a lightning strike near the subdivision clubhouse serving as the polling place. But a news release says the office was later told the building owner had changed the locks and election judges didn’t have the correct key.