Thousands of voters in Tennessee were at risk of being blocked from casting regular ballots when early voting opened this week, as officials struggled to process a surge of new registrations ahead of Nov. 6 elections to determine control of the U.S. Congress.

The delay disproportionately affected the area around Memphis, a majority African-American city, leading activists to charge the Republican-controlled state government has not done enough to protect the rights of young and minority voters.

State officials, however, said they were simply struggling to keep up with a surge in paperwork ahead of Election Day.