An expected lawsuit challenging North Dakota's ban on gay marriage will leave no state without an active lawsuit challenging such bans.

Minneapolis-based civil rights attorney Joshua Newville told The Washington Post that “there will be a case filed challenging North Dakota's same-sex marriage ban.”

Newville is representing six gay couples in a lawsuit challenging South Dakota's restrictive marriage ban.

(Related: Six couples challenge South Dakota's gay marriage ban.)

Newville confirmed that the lawsuit would be filed within six to eight weeks.

On Wednesday, Thompson Mayor Karyn Hippen joined Mayors for the Freedom to Marry, making her the first mayor in the state to endorse marriage equality. Hippen leads a town with fewer than 1,000 residents.

A large majority (73%) of North Dakota voters in 2004 approved a constitutional amendment defining marriage as the union of a man and a woman. The amendment also prohibits the state from recognizing gay couples with civil unions or domestic partnerships and reinforces state laws.