DENVER (AP) -- Abortion opponents will begin gathering petition signatures to put a third measure to ban abortions on statewide ballots.

More than 3,000 volunteers are expected to begin circulating petitions on Wednesday.

The Colorado Supreme Court rejected a legal challenge from Planned Parenthood of the Rocky Mountains earlier this month.

Planned Parenthood wanted the court to block a sweeping measure from Personhood Colorado to outlaw abortions, even in cases of rape and incest.

The measure still needs 86,000 signatures before it would earn a place on November ballots. Similar measures were overwhelmingly defeated by Colorado voters in 2010 and 2008.

This year's Personhood proposal would also ban stem-cell research and some fertility treatments.

A Planned Parenthood spokeswoman says the group is prepared to defeat this attempt.

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