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Voters in New Mexico's largest city Tuesday were deciding whether to ban late-term abortions in a first-of-its-kind municipal election that was being closely watched as a possible new front in the abortion wars.

The special election was expected to draw more voters than last month's mayoral contest. But the outcome was anyone's guess following an emotional and graphic campaign that included national groups and hundreds of thousands of dollars in advertising.

Police were stationed near polling places around the city as protesters from both sides tried to persuade voters who were lining up before the polls closed. One school reported an hour wait.

Michelle Halfacre said she cast her ballot in favor of the proposal, which would ban abortions after 20 weeks except to save the mother's life.

"I had an abortion when I was young, and I regret it," Halfacre said. "I don't believe in it."

But Jonathan Cottrell, a crisis hotline volunteer, said he voted against the proposal because he believes it marks the beginning of a "slippery slope to ban abortion in general."

"I feel that women have the right to choose what to do to their body," Cottrell said.

NARAL Pro-Choice America President America Ilyse Hogue said this is the first municipal ballot on abortion that she knows of, and her group is watching the election closely.

A legal challenge is expected if the referendum passes. Attorney General Gary King, a Democrat, has said he believes the measure is unconstitutional.

The issue was put to voters after former Operation Rescue interns and anti-abortion "missionaries" Tara and Bud Shaver moved here three years ago to target Southwestern Women's Options, one of a handful of clinics in the country that perform late-term abortions.

Tara Shaver says her group, Project Defending Life, gathered signatures to get the measure on the city ballot after failing to make headway in the Democratic-controlled Legislature.

Asked if other cities with late-term abortion clinics might be targeted in the future, Shaver said, "We are encouraging people to see what can be done at the city level. ... We are starting to get calls from people asking us how to do what we have done."