TALLAHASSEE, Fla. - Florida Attorney General Bill McCollum is conducting an antitrust investigation of a voting-machine company merger that would create a near-monopoly over the levers of democracy in Florida and much of the United States.

McCollum's office has issued at least six subpoenas covering every major voting-machine company as part of a civil investigation of Election Systems & Software's $5 million acquisition of Diebold Inc.'s elections division - a merger that would give a private company too much power over the machines used to cast votes, voting-rights groups say.

"Our office engaged in this issue because anti-competitive behavior can seriously harm consumers," McCollum said in a written statement. "Competitive behavior encourages the best products be available to consumers, including technology, particularly in a market as sensitive as the voting systems market."

Under the state's 1980 antitrust law, McCollum could persuade a court to levy fines against ES&S or prevent the company from operating in Florida. By next year, the company is expected to be the exclusive provider of voting machines and services in 65 of the 67 counties in Florida, a swing state.

ES&S's purchase of the competitor company gives it control of the voting machines in nearly 70 percent of the nation's precincts, according to a federal lawsuit in Delaware filed by a rival company, Hart Intercivic. The U.S. Justice Department is conducting its own inquiry.

Under the acquisition announced Sept. 2, ES&S will provide election services to 92 percent of Florida's 11.2 million voters.

McCollum's investigation came to light Wednesday after eight voting-rights groups sent him a letter urging him to open an inquiry - unaware that his office had already opened its investigation Sept. 10. The first subpoena was sent out Oct. 2.

McCollum's spokeswoman, Sandi Copes, said the office could not comment on a pending investigation.

The subpoenas show that McCollum is seeking every type of document the voting-machine companies have, from "pencil jottings" to memos to canceled checks and even electronic images of Web sites.

Spokesmen and lawyers for ES&S, Diebold, and the other voting companies could not be reached or would not comment on the case.