NASHVILLE (AP) - Abortion rights supporters on Tuesday asked a federal judge to toss out a 2014 constitutional amendment that made it easier to restrict abortion in Tennessee.

They claim the way the vote was counted was unfair and favored supporters of the amendment, which passed with 53 percent voting in favor.

Supporters and opponents spent more than $5.5 million on the campaign over Amendment 1. Much of that was raised by abortion rights advocates from Planned Parenthood affiliates across the country who fought the change.

Amendment 1 added language to the Tennessee constitution making clear that it does not protect abortion. Once the constitution was changed, the General Assembly passed laws requiring clinics to meet the strict standards of surgical treatment centers and requiring women seeking abortions to undergo mandatory counselling and then wait 48 hours before getting an abortion.

Tennessee previously was an outlier in the South, with fewer abortion regulations than surrounding states.

During the campaign, supporters of Amendment 1 portrayed Tennessee as an "abortion destination," playing up that almost 23 percent of the women getting abortions in Tennessee at the time were from out of state. But another campaign led by anonymous supporters of the amendment is what led to the current court challenge.

On social media and in churches around the state, people were urged to "double your vote" by skipping the governor's race and voting "yes" on Amendment 1. That's because the state constitution that says amendments must be passed by "a majority of all the citizens of the state voting for governor, voting in their favor."

The state says that language refers to how many people have to vote in favor of an amendment for it to be ratified. It is not enough for an amendment to simply have more "yes" votes than "no" votes. The number of "yes" votes also has to be equal to at least th e number of people voting for governor plus one, a simple majority.

So if 1,000,000 vote for governor, at least 500,001 must vote in favor of the amendment. But if fewer people vote for governor, fewer votes are needed to pass an amendment.

Plaintiffs' attorney Bill Harbison argued in federal court in Nashville on Wednesday the state is incorrectly interpreting the way amendment votes should be counted. He said the language of the constitution - "a majority of all the citizens of the state voting for governor" - refers not to the number of voters, but to the voters themselves. That is, only voters who cast ballots in the governor's race should have their votes counted on the amendment.

Because the state looked only at the number of voters and not at the voters themselves, election officials created a situation where "yes" votes can hold more weight than "no" votes, according to Harbison. He said that was in violation of the plaintiffs' federal due process an d equal protection rights.

He suggested the fact that, for the first time, there were more votes on an amendment than in the governor's race, shows the campaign to manipulate the vote was successful. And he said a ruling in favor of the state's interpretation would invite future manipulation.

Deputy Attorney General Janet Kleinfelter, arguing for the state, said there is no proof that voters actually participated in the voting scheme pushed by some Amendment 1 supporters. She said there may simply have been more voter interest in the amendment than in the governor's race, in which a political unknown ran against popular incumbent Gov. Bill Haslam.

Kleinfelter also said the state has counted votes on amendments in the same way for more than 100 years.

"State officials, election officials and courts shouldn't interpret the constitution based on how political campaigns might try to manipulate it," she told the court.

U.S. District Judge Kevin Sharp said he will rule as soon as possible.