By The Associated Press

Arizona voters may be asked in November to approve a dramatic change in the state's election system, allowing an open, nonpartisan primary election.

A group calling itself the Open Government Committee filed petitions with an estimated 365,000 signatures on them with the secretary of state's office on Thursday, hours ahead of the deadline for initiative petition filings.

Under the measure, any voter regardless of partisan affiliation could vote for any primary election candidate for partisan office. The two candidates receiving the most votes in the primary would advance to the general election, regardless of partisan affiliation.

Leaders of both major political parties have declared opposition to the proposal. Proponents say it would bring balance to the elective process in Arizona, where one-third of the registered voters are not affiliated with either the Democrats or the Republicans.

Currently, a voter registered with a party can vote only for primary election candidates from that party, though independents can pick candidates on one party's ballot. Also, only the top vote-getter from each party now advances to the general election.

To make the ballot, slightly more than 259,000 signatures must be valid, and the secretary of state's office has 20 days to certify them.

Elections officials also expected a last-minute filing of petitions for a proposal on states' rights.

Petitions for an initiative to extend the 1-cent school sales tax were filed last week, but Secretary of State Ken Bennett rejected them because of a language difference between the paper copy of the initiative and what was circulated with petitions.

Sponsors of the proposal have filed suit, and a hearing is scheduled for July 18 in Maricopa County Superior Court.

A secretary of state's spokesman said via email that the office will not make public which initiative petitions were filed until the 20-day review is completed.

A dozen or more petition drives were recorded with the secretary of state last year and earlier this year, but most are not expected to be filed by Thursday's deadline. Thus, they won't be on the November ballot.

Your Vote 2012: The AZPM Election Center