TALLAHASSEE, Fla. — What first appeared to be an isolated problem in one Florida county has now spread statewide, with election officials in at least seven counties informing prosecutors or state election officials about questionable voter registration forms filled out on behalf of the Republican Party of Florida.

State Republican officials already have fired the vendor it had hired to register voters, and on Thursday took the additional step of filing an election fraud complaint against the company, Strategic Allied Consulting, with state officials.

A spokesman for Florida’s GOP said the matter was being treated very seriously.

“We are doing what we can to find out how broad the scope is,” said Brian Burgess, the spokesman.

Florida is the battleground state where past election problems led to the chaotic recount that followed the 2000 presidential election.

The Florida Democratic Party called on the state to “revoke” the ability of state Republicans to continue to register voters while the investigation continues. Oct. 9 is the deadline to register to vote in the Nov. 6 presidential election.

“It is clear that the Republican Party of Florida does not have the institutional controls in place to be trusted as a third-party, voter registration organization,” said Scott Arceneaux, executive director of the Florida Democratic Party.

The Republican Party of Florida has paid Strategic Allied Consulting more than $1.3 million, and the Republican National Committee used the group for nearly $3 million of work in Nevada, North Carolina, Colorado and Virginia. Federal election records also show that Republican parties in North Carolina, Colorado and Virginia had paid the company.

The company said earlier this week that it was cooperating with elections officials in Florida. It said the suspect forms were turned in by one person, who has been fired.

“Strategic has a zero-tolerance policy for breaking the law,” Fred Petti, a company attorney, said Thursday.

An email request to the company seeking additional comment, following the company’s instructions, was not immediately returned Friday.

In Florida, it is a third-degree felony to “willfully submit” any false voter registration information, a crime punishable by up to five years in prison.

In recent years, Florida’s Republican-controlled Legislature — citing suspicious voter registration forms turned in by the Association of Community Organizations for Reform Now, or ACORN — has cracked down on groups holding voter registration drives.

The League of Women Voters filed a federal lawsuit against some of the restrictions and Florida agreed earlier this month to drop a new requirement to turn in registration applications within 48 hours after they are signed. The state has reinstated a 10-day deadline.

The questionable forms tied to the Republican Party have showed up in South Florida, including Miami-Dade, as well as northeast Florida and the Florida Panhandle.

Election officials in Escambia and Santa Rosa counties on Thursday handed over more than 100 suspect forms to local prosecutors. They did so days after officials in Palm Beach County also alerted prosecutors.

Ann Bodenstein, the elections supervisor for Santa Rosa County, said her staff started raising questions after an employee saw a form that changed the home address of a neighbor.

Paul Lux, election supervisor for Okaloosa County, said questionable forms in the Florida Panhandle appear to have all come from Strategic’s effort based at the local Republican Party headquarters. He said his office has turned up dozens of suspect forms.

Lux said there have been forms that listed dead people and were either incomplete or illegible. He met with local prosecutors on Friday, but added that his staff was still going through hundreds of forms dropped off by Strategic employees.

Lux, who is a Republican, said he warned local party officials earlier this month when he first learned the company was paying people to register voters.

“I told them ‘This is not going to end well,”’ Lux said.

But Lux added that he did not blame the Republican Party of Florida.

“I can’t place the blame on RPOF if they hired a firm and that firm wasn’t following the rules they were given to follow,” Lux said.

The state party filed the complaint against Strategic Allied Consulting with state election officials, who can refer the case to the Florida Department of Law Enforcement if it is found legally sufficient.