About 500 supporters of a constitutional amendment banning gay marriage in Iowa rallied Tuesday at the Statehouse, the Des Moines Register reported.

A resolution authorizing a ballot question that would define marriage as a heterosexual union in the constitution has cleared the Republican-led House. But Majority Leader Michael Gronstal has blocked the measure in the Democrat-led Senate. Gronstal has said he understands his actions could cost him his job.

Social conservatives continue to fight against the 2009 unanimous Iowa Supreme Court decision that brought gay marriage to the Midwest.

Demonstrators, many clad in red, demanded the right to vote on the marriage amendment, chanting “Let us vote” at the rally organized by Bob Vander Plaats' socially conservative group The Family Leader.

The Rev. Keith Ratliff Sr., the pastor of Maple Street Missionary Baptist Church in Des Moines and the president of the Iowa-Nebraska chapter of the National Association for the Advancement of Colored People (NAACP), claimed that gay rights advocates had “hijacked” the civil rights debate.

“That is an insult to the civil rights movement,” Ratliff said. “Deviant behavior is not the same as being denied your right to vote.”

Meanwhile, gay marriage supporters lobbied lawmakers inside the Capitol rotunda.