Colorado, the last state with a measure pending this year that would ban abortion outright, will not vote on the so-called Personhood Amendment in November after it failed to garner the number of petition signatures required to make the ballot, according to reports. Backers of the initiative have lawyered up, promising to fight the decision.

Proponents of the measure submitted 106,199 signatures. After culling for invalid signatures, 82,246 were left standing, falling short of the required 86,106, Colorado Secretary of State Scott Gessler announced.

There is a 30-day window to challenge the secretary of state's findings, which Personhood Colorado spokeswoman Jennifer Mason promised would occur.

"We have hired an election attorney," she told the Denver Post. "We are confident we will still be on the ballot in November. We're certain of it."

Gessler's announcement led opponents of the measure to denounce its backers.

"Women across Colorado are sighing with relief," said Vicki Cowart, chief executive officer of Planned Parenthood of the Rocky Mountains, according to the Denver Post. "Health decisions should be left to a woman, her doctor, her family and her faith - not politicians."

Initiative 46 was the last "Personhood Amendment" in the nation. It would have changed the state constitution to require the protection of life for "all human being at any stage of development," a backdoor way of banning abortion. The measure would also put a stop to embryonic stem-cell research and some fertility treatments.

It has been on Colorado ballots twice before, and was trounced both times, according to the Washington Post.