Salt Lake City Mayor Rocky Anderson's push to offer health-care benefits to domestic partners of city employees has gay marriage advocates and their opponents accusing each other of flip-flopping in their legal analyses of Utah's constitutional ban on gay marriage.

But one thing they do agree on is the issue will likely spark an ornery fight — at the courthouse and the statehouse — in the coming months.

If Anderson signs an executive order extending dental and medical benefits to nonmarried domestic partners, as he has promised to do before this November, opponents have threatened to file suit. Further complicating the matter, that legal fight may be rendered meaningless if one state lawmaker fulfills his promise to introduce legislation prohibiting Anderson's plan.

And as Anderson prepares to engage the fight, he has the backing of the majority of his constituents. A new Dan Jones & Associates poll for the Deseret Morning News and KSL-TV shows 54 percent of Salt Lake City residents favor Anderson's plan to extend health benefits to domestic partners of city employees. Still, showing the issue is controversial even in politically liberal Salt Lake City, a sizable number, 42 percent, oppose it.

The controversy over domestic partner benefits really erupted in Utah last year as voters considered Amendment 3. Then, the anti-gay marriage camp argued that Amendment 3 wouldn't prevent any company or government from extending health benefits to nonmarried dependents.

In contrast, gay marriage advocates said that an amendment provision reading "no other domestic union, however denominated, may be recognized as a marriage or given the same or substantially equivalent legal effect" would stop governments from extending benefits to domestic partners.

Fast-forward to 2005 and gay marriage advocates have changed their tune.

Scott McCoy, a gay attorney who led the opposition to Amendment 3 and is now a state senator, said he now believes current state law and Amendment 3 allow for benefits such as those proposed by Anderson.

McCoy counters accusations of flip-flopping by saying Amendment 3 folks have switched their story by complaining about Anderson's proposal.

"The Yes! for Marriage folks flat out said if a local city wants to offer domestic partner benefits, it can," McCoy said this week. "If Amendment 3 is just about marriage, I don't see this has anything to do with marriage."

Jane Marquardt, another gay attorney who is the current chairwoman of Equality Utah, agrees it is those anti-gay marriage advocates who have done the 180.

They were the ones who had the legal opinion saying "you can't plausibly argue that extending a few basic benefits would be prohibited by Amendment 3," she said.