Two Iowa lawmakers have introduced bills which seek to constitutionally define marriage in the state as a heterosexual union.

The measures, introduced in the House and Senate by Republicans Senator Dennis Guth and Rep. Greg Heartsill, are backed by 21 other GOP legislators, according to The Des Moines Register.

The move comes nearly six years after the Iowa Supreme Court's unanimous decision that first brought marriage equality to the Midwest and as dozens of such bans face challenges in federal and state courts.

Guth has backed previous efforts to reverse the court's decision.

In 2013, he stunned colleagues when he claimed that gays pose “health risks” to his family.

“Just as there are multiple ways that your smoking hurts me, such as second-hand smoke, so it is with same-sex relationships. There are health risks that my family incurs because of the increase of sexually transmitted infections that this lifestyle invites. For example, there are more and more medical tests required before giving blood or giving birth,” he said.