At a rally on Tuesday calling on Iowa lawmakers to advance a constitutional amendment barring gay marriage, Brian Brown of the National Organization for Marriage (NOM) told attendees that they were being denied the right to decide the issue, the Des Moines Register reported.

The 45-minute morning rally held in the statehouse rotunda was sponsored by The Family Leader, whose president and CEO, Bob Vander Plaats, led an unsuccessful 2010 campaign to govern the state fueled mostly on opposition to gay marriage, NOM, the nation's most vociferous opponent of marriage equality, and

The amendment would overturn the Iowa Supreme Court's unanimous 2009 ruling legalizing gay marriage.

Last year, the Republican-controlled House easily approved the measure, but Senate President Mike Gronstal, a Democrat, blocked it from reaching the Senate floor, angering conservatives who have threatened to oust him.

Gronstal over the weekend reiterated his opposition to the amendment, saying that he believes rights should not be put to a popular vote.

Vander Plaats told supporters that marrying people of the same gender would lead to parents marrying their children.

“If we want marriage equality, let's just stop for a second. Why stop at same-sex marriage? Why not have polygamy? Why not have a dad marry his son or marry his daughter. If we're going to have marriage equality, let's open this puppy up and let's have marriage equality,” Vander Plaats said. “Otherwise, let's stick to the way God designed it – one man and one woman, period.”

Brown said Democrats were attempting to deprive opponents of the right to vote on the amendment.

“We hear that this is about civil rights, and that those of us who oppose the redefinition of marriage are somehow bigots,” Brown said. “And yet, what Dr. Martin Luther King called the most important civil right – the right to vote – these very same folks are trying to deprive us of this right.”