TALLAHASSEE, Fla. — Florida Gov. Ron DeSantis extended the state's voter registration deadline Tuesday after he said heavy traffic crashed the state's online system and potentially prevented thousands of enrolling to cast ballots in next month's presidential election. Several progressive groups are suing for an additional extension.

DeSantis extended the deadline that expired Monday until 7 p.m. Tuesday. In addition to online registration, DeSantis ordered elections, motor vehicle and tax collectors offices to stay open until that hour for anyone who wanted to register in person. He also said any forms postmarked by Tuesday would be accepted.

Voting and minority rights groups responded with a federal lawsuit, saying the confusion required more time, but DeSantis disagreed, saying the seven-hour outage required a comparable extension. The problems began about 5 p.m. Monday and continued until the midnight deadline.

"You can have the best site in the world, but sometimes there are hiccups," DeSantis said during a press conference at The Villages, a large retirement community in central Florida. "If 500,000 people descend at the same time, it creates a bottleneck."

Dream Defenders, New Florida Majority, Organize Florida, LatinoJustice PRLDEF and others filed their lawsuit in Tallahassee, saying at least two additional days were needed to give those denied access enough time to learn of the extension and respond. They said that anything less would be voter suppression.

"No voter should be denied their right to vote during a global health pandemic because Florida did not have a functioning online voter registration system," said Jorge Vasquez, power and democracy director at Advancement Project National Office, one of the suing groups. No hearing was immediately set.

There were no immediate reports of major glitches during the additional period through Tuesday evening that potentially allowed thousands more people to register in Florida's 67 counties. In Leon County, for example, there were nearly 2,000 additional transactions — including new or updated registrations — by late-afternoon, county Elections Supervisor Mark Earley said.

Florida Secretary of State Laurel Lee, who oversees the voting system, said that at times on Monday the online registration system "was accessed by an unprecedented 1.1 million requests per hour." Officials said many of the requests were likely repeated attempts by those who failed to get into the system, which went online in 2017. There were complaints before the 2018 registration deadline that the system was sluggish.

Lee's office is investigating the overload.

"At this time, we have not identified any evidence of interference or malicious activity impacting the site," she said in a statement Tuesday night. "We will continue to monitor the situation and provide any additional information as it develops."

CEO Matthew Prince of Cloudflare, the internet infrastructure company that protects Florida's elections website, tweeted that he has seen no indication that any voter registration systems it protects had been hit by a cyberattack. The company declined further comment.

The FBI and the Cybersecurity and Infrastructure Security Agency warned elections officials nationwide last week that cyberattacks could disrupt their systems during the run-up to the election. They particularly noted "distributed denial-of-service" attacks, which inundate a computer system with requests, potentially clogging up servers until the system becomes inaccessible to legitimate users.

The volume of requests that overwhelmed the Florida registration site Monday was not consistent with denial-of-service attacks, which typically render websites unavailable with barrages of several hundred million requests per second.

The potential for outside meddling is an especially sensitive issue in Florida, a key battleground state in November's election between President Donald Trump and his Democratic challenger, former Vice President Joe Biden. The state has lingering questions about Russian hacking during the election four years ago.

Biden tweeted Tuesday that the Republican governor's decision to extend the deadline "is a win for our democracy."

Whatever caused the disruption, it threw up a roadblock for those trying to register. Sarah Dinkins, a Florida State University student, tried to help her younger sister register Monday night. They began trying about 9 p.m. and by 10:30 p.m. had not been successful.

"I feel very frustrated," she said. "If the voting website doesn't work, fewer people potentially Democratic voters will be able to vote."

The outage impacted many Florida felons, who just received the right to vote in a 2018 state referendum that passed overwhelmingly — if they have completed probation and don't have any outstanding fines or fees. Murderers and sex offenders are still banned.

Desmond Meade, executive director of The Florida Rights Restoration Coalition, said the group heard from dozens of felons who couldn't register.

This is not the first major computer shutdown to affect the state government this year. For weeks in the spring, tens of thousands of Floridians who lost their jobs because of the coronavirus pandemic couldn't file for unemployment benefits because of repeated crashes by that overwhelmed computer system, delaying their payments. DeSantis replaced the director overseeing that system but blamed the problems on his predecessor, fellow Republican Rick Scott, who is now a U.S. senator.

Democrats jumped on the latest issue, saying it and the unemployment fiasco showed that the DeSantis administration is inept and accused it of trying to stop people from voting.

"The utter incompetence of Gov. Ron DeSantis in allowing the state's voter registration website to crash on the very last day to register for the upcoming November election is, sadly, completely believable," U.S. Rep. Debbie Wasserman Schultz said. "His administrative buffoonery in operating the state's unemployment system telegraphed today's executive ineptitude. However, this particular blunder intimates a continuing pattern of voter suppression that the governor has become notorious for."