Two weeks before California's presidential primary, a group alleging widespread security holes in electronic voting machines asked a judge Tuesday to make counties install new safeguards.

Citizens from four counties requested a temporary restraining order in Sacramento County Superior Court. They asked that up to 18 counties using machines made by Ohio-based Diebold Election Systems (search) add more safeguards to protect them against hackers.

Court officials scheduled a hearing for Wednesday on that issue and an accompanying lawsuit seeking to stop the state and Diebold from using "insecure" voting machines. California counties are using three versions of Diebold systems to register votes and using the company's software to tally them.

Diebold has consistently maintained that its voting systems are secure.

The new legal challenge comes as 10 counties are balking at Secretary of State Kevin Shelley's directive to conduct random testing and other measures to guarantee the voting machines' accuracy in the March 2 primary.

Counties have claimed that Shelley is overstepping his authority and misleading the public about the machines' vulnerability. They say his plan will cost too much, although Shelley has said the state will reimburse counties for the pre-election costs.

Tuesday's court filing alleges that Shelley's directive is inadequate, citing reports by security experts calling the Diebold systems "vulnerable to vote tampering both by company insiders and outside computer hackers."

Four in 10 California voters will likely use electronic voting systems from Diebold or Sequoia Voting Systems in the primary.

Attorney Lowell Finley said that after the March election he will seek even more stringent security updates "or in the alternative, prohibit the use of Diebold voting systems in California."