DENVER -- Supporters of Colorado's personhood initiative need 15,690 signatures to get the issue on the November ballot.

They turned in three times that many Thursday afternoon, and then announced they may sue the state over a requirement that petition circulators provide an acceptable form of identification to notary publics.

That new requirement led to some signatures being ruled invalid the first time they were turned in.

"We've had people who had 1,000 signatures tossed because the notary hadn't been notified by the state of this change in the law," said Gualberto Garcia Jones, director of Personhood Colorado.

Garcia Jones said that some of the group's best volunteers were people who had long working relationships with the notaries.

He said the notaries used that long personal relationship as a form of ID.

Rich Coolidge, spokesman for the Secretary of State's office, said petition circulator training guides have been available since July of 2009.

The notary requirements are listed on page 8.

The sample affidavit includes space for the notary to log what evidence was used to establish ID.

Garcia Jones said they'll know in a month or so whether they'll follow through with the lawsuit.

"We want to do it to vindicate the hard work of the volunteers," he said.

Opponents of the measure told 7NEWS that the petition law is clear.

"If you simply go to the law it is very clear about what kind of ID is required in order to sign a petition," said Leslie Durgin of Planned Parenthood of the Rocky Mountains. "There is no ambiguity about it."

Durgin said the proposed personhood initiative would force a change in thousands of other laws regarding inheritance, property and ownership.

“Which of course would keep the state legislature tied up, literally for years,” Durgin said.

The Secretary of State has 10 days to verify the latest batch of signatures.

If the initiative makes it on to the ballot, it won’t be the first time.

Voters rejected the Personhood amendment the last time by a 3-1 margin.