DENVER - Colorado's secretary of state has declared many of the state's electronic voting machines to be unreliable, but said yesterday that some could still be used in November if a software patch can be installed.

Other machines that failed could be replaced with equipment certified for use in other states, Secretary of State Mike Coffman said.

The day after he decertified three of the four voting-equipment manufacturers allowed in the state, affecting six of Colorado's 10 most populous counties, Coffman met with a task force of state lawmakers to discuss what could be done.

Either of Coffman's solutions mentioned yesterday would have to be approved by the legislature. The lawmakers on the task force gave no indication of whether they would accept the proposals.

In his announcement Monday, Coffman said Colorado's actions would have national repercussions. "What we have found is that the federal certification process is inadequate," he said.

The decertification decision, which cited problems with accuracy and security, affects electronic voting machines in Denver and five other counties. A number of electronic scanners used to count ballots were also decertified.

Coffman would not comment on what his findings mean for past elections, despite his conclusion that some equipment had accuracy issues.

"I can only report," he said. "The voters in those respective counties are going to have to interpret" the results.

Coffman said in March that he had adopted new rules for testing electronic voting machines. He required the four systems used in Colorado to apply for recertification.

The machines are manufactured by Premier Election Solutions, formerly known as Diebold Election Systems; Hart InterCivic; Sequoia Voting Systems; and Election Systems and Software. Only Premier had all its equipment pass the recertification.

In the Philadelphia region during the midterm congressional elections last year, Montgomery County used an updated version of the Sequoia Advantage touch-screen electronic machine. According to the New Jersey Division of Elections' Web site, most of that state's counties use Sequoia machines.

Sequoia said it was reviewing the 175-page report. Ken Fields, spokesman for ES&S, said the decertification was based on additional requirements recently imposed, while Peter Lichtenheld, a spokesman for Hart InterCivic, said his company planned to appeal based on how the state conducted the tests and maintenance of its machine.

In Ohio, the state that narrowly gave President Bush his win in 2004, a review concluded last week that electronic voting machines were vulnerable to security breaches and human error. Gov. Ted Strickland said Monday that the state must act on the study's findings by November's vote.

Inquirer staff writer Thomas Fitzgerald contributed to this article.