The number of people casting early ballots in the runoff election for one of Georgia’s seats in the US Senate has already broken records since the process began on the weekend, with some counties posting staggeringly long wait times at early voting sites during the first days of early voting.

Reports on Monday’s turnout varied from more than 250,000 voters to more than 300,000 on the first day of statewide early operation of the polls. Some counties began earlier.

As of mid-afternoon Tuesday, 11 of 27 early voting locations in Fulton county, the state’s most populous, had a wait time of at least an hour. Several reported wait times of more than two hours.

In Gwinnett county, in suburban Atlanta, eight of the 11 early voting sites reported wait times of at least 45 minutes, including three sites with wait times of more than an hour. Zach Manifold, the county’s election administrator, attributed the long waits to “heavy turnout and only seven days of advance voting”. Georgia Republicans passed a law last year that shortened the runoff period from nine weeks to four.

Manifold said his county was operating at “maximum capacity on check-ins” and was equipped to handle about 20,000 voters a day. Nearly 18,000 people voted in person in the county on Monday, according to state data.

The incumbent Democrat, Raphael Warnock, and his Republican challenger, Herschel Walker, are neck and neck as the election on 6 December approaches. The deputy secretary of state, Gabriel Sterling, said it was the largest in-person early voting day in Georgia history.

Neither candidate got above the 50% threshold in the midterm elections earlier this month, so under Georgia rules the fierce race went to a runoff.

With just a week to go before polls close, progressives in Georgia are leaving nothing to chance. A coalition of progressive groups has launched a massive canvassing effort for the Democratic party.

Leaders of the coalition, known as Georgia Organizers for Active Transformation, said on a Monday press call that they now have 2,500 canvassers knocking on 200,000 doors a day, and that canvassers have knocked on more than 2.5m doors in the three weeks since election day.

The early voting numbers appear to indicate that the effort is paying dividends. According to the progressive group Progress Georgia, African Americans and women are currently outpacing their high turnout levels in the 2020 general election. Given that those constituencies lean toward Democrats, the early voting data could provide some reassurance to Warnock’s camp as he defends a seat he has only held since 2021.

“Georgia voters know exactly what’s going on,” said Hillary Holley, a coalition leader and the executive director of Care in Action. “They know what the stakes are, and they want Warnock to remain representing them for six additional years.”

Despite the extensive efforts of progressive organizers, the state’s early voting operation has run into some significant issues. Many voters reported long lines at polling places over the weekend, with Warnock himself waiting in line for about an hour on Sunday to cast his vote.

Misunderstandings about voting rules appear to be widespread, according to Holley. “Every time basically our canvassers reach a voter at their house they’re saying, ‘Thank you so much because we are so confused about when we can go vote,’” she said.

Part of that confusion stems from a judge’s last-minute ruling that counties could allow early voting to occur on the Saturday after the Thanksgiving holiday.

Georgia election officials had initially said that early voting could not take place on that day, but the Warnock campaign won a legal challenge to expand voting hours.

Stephanie Jackson Ali, policy director of the progressive group New Georgia Project, said: “Our call is for counties to continue the fight to get more locations open, to continue the fight to keep your counties open late, and for our voters to stay in line.”