Citizens of Iowa Senate District 18 received a robocall on Monday night instructing them to call Democratic candidate Liz Mathis and ask what homosexual acts she approved of, according to the Des Moines Register.

“Homosexual marriage obviously involves homosexual sex. So before you support Liz Mathis, call her at 319-899-0628 and ask her which homosexual sex acts she endorses,” the automated call said.

Mathis is facing off against her Republican opponent, Cindy Golding, in the November 8 special elections. Mathis supports marriage rights for same sex couples, while Golding supports a proposed constitutional marriage amendment that would define marriage as solely between one man and one woman.

The election could determine the fate of the proposed amendment. Democrats have a majority in the state Senate, but if Golding had won control of the Senate would have been split equally.

The automated message was made by a group calling itself Citizens for Honesty and Sound Marriage in Iowa. Supporters of "traditional marriage" have sent out fliers in support of Golding, but deny any involvement with the calls and claim the group is bogus.

"Yesterday a phony group claiming to support marriage launched robocalls that were so offensive they clearly were designed to turn voters away from Cindy Golding because she supports marriage between one man and one woman," Brian Brown, president of the National Organization for Marriage (NOM), said Tuesday in a statement.

"NOM and the Family Leader have been out front advocates for Cindy Golding’s election for weeks, because she will help ensure that the voters of Iowa have the opportunity to vote on the definition of marriage in our state," added Bob Vander Plaats, president and CEO of Family Leader.

The two groups called on the Attorney General to launch an investigation into the "phony" robocalls, which they said were meant to "steal the election."

Golding's campaign also denied having any involvement with the automated messages.

Mathis won the race with 56 percent of the vote, according to the Des Moines Register.

“I pledge to the voters of this district: I will go to the Capitol and fight for you every day. I will be your voice in the State Senate,” she said.

Updated 11:53pm ET