Support remains strong for a proposed amendment that would write a ban on same-sex marriage into the Utah Constitution, according to a new Deseret Morning News/KSL-TV poll conducted by Dan Jones & Associates.

Sixty-three percent of the 915 registered voters polled statewide said they'd vote in favor of the amendment this November.

The amendment would define marriage as "the legal union between a man and a woman"; it would also provide that "no other domestic union may be recognized as a marriage or given the same or substantially equal legal effect."

The poll, conducted Sept. 6 to 9, showed 30 percent said they'd vote against the amendment, and 7 percent either said they were undecided or didn't know. The poll's error margin was 3 percent.

Support for amending the constitution was virtually unchanged from previous Deseret Morning News/KSL-TV polls on the issue. However, when voters were asked about their level of support for each part of the amendment, support was weaker for the second clause, which has been the main focus of debate.

Supporters say the wording is needed to prevent so-called "counterfeit marriages" such as civil unions and domestic partnerships.

Opponents say the same wording would strip away legal protections from all couples not legally married, such as inheritance rights and hospital visitation; and would deny a group of citizens the right to seek legal benefits.

While 80 percent supported a constitutional definition of marriage, only 56 percent supported the second sentence.

Pollster Dan Jones said the poll shows an unusually low number of undecided voters on the amendment.

"On ballot initiatives and amendments, people don't really make up their mind until 15 days before the election," Jones said.

Jones said the results show if the initiative were voted on today, it would pass.

However, he said, both sides still have the opportunity to sway those voters who are undecided or who said they "somewhat support" (13 percent) or "somewhat oppose" (10 percent) the amendment's second part.

Scott McCoy, Don't Amend Alliance campaign manager, agrees there is an opportunity in the poll's finding that only 43 percent of voters "strongly support" the amendment's second part.

"Voters have to vote on both things together," McCoy said. "They're going to have to decide whether or not they can stomach Part 2, in order to get Part 1. I'm still confident come election day we'll win."

Susan Roylance, president of Yes! for Marriage, one of three campaigns in support of the amendment, said the poll's results are encouraging, considering what she calls "misinformation" presented by amendment opponents.