Iowa Democrats on Wednesday selected Liz Mathis for a Senate race likely to determine whether gay marriage is debated in the chamber.

Mathis, 53, a former news anchor, is the Democrats' nominee for a special November 8 Senate race for the seat being vacated by Democratic State Senator Swati Dandekar. Senate District 18 predominantly votes Republican.

The Democrat-controlled Senate, under the leadership of Majority Leader Michael Gronstal, has kept an effort to repeal the state's gay marriage law at bay. In February, the Republican-controlled House approved a measure that seeks to put a question on the ballot that would define marriage in the Iowa Constitution as a heterosexual union – and thereby reverse the 2009 Iowa Supreme Court ruling that brought gay marriage to the Midwest.

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

But Republican Governor Terry Branstad's appointment of Dandekar to the Iowa Utilities Board could result in Democrats losing their one-seat Senate majority. And by extension, stripping Gronstal of power. In previous sessions where the Senate was divided, leaders from both parties took turns on alternating weeks running the chamber.

Branstad has dismissed suggestions that the appointment was political.

Mathis will face Republican rival Cindy Golding in what is expected to become a heated contest. Neither woman has previously held elected office, but in 2002 Golding, 58, ran for the Iowa House.

During an informal interview with Iowa Politics, Mathis said she supported “the judges approval, the judge's upholding of the constitution.”