An early morning bid by freshman Iowa State Senator Kent Sorenson to push for a gay marriage ban in the chamber has failed.

All 26 Democrats united to defeat 24 Republicans on the motion that sought to suspend the chamber's rules.

Sorenson's motion was framed as a showdown on gay marriage by socially conservative group The Family Leader, the state's most vociferous opponent of the Iowa Supreme Court's 2009 unanimous decision that brought gay marriage to the Midwest.

In an email to supporters, the group's chairman, Danny Carroll, explained that Sorenson was planning to “file numerous amendments and use any other tactic at his disposal” in order to force a vote on the Iowa Marriage Amendment (IMA), a joint resolution that seeks to put a question on the 2013 ballot that would define marriage in the Iowa Constitution as a heterosexual union. The IMA would ban any legal recognition of gay and lesbian couples, including civil unions and domestic partnerships.

Senate Majority Leader Mike Gronstal has vowed to block the measure from reaching the Senate floor.

Gronstal denied Carroll's claims that Thursday's vote was on gay marriage.

“It is not a vote on the constitutional vote, but I understand that people can lie and say it is,” Gronstal told the Des Moines Register.

The IMA cleared a key House panel on Monday. A House hearing on the measure is set for next Monday.