SIOUX FALLS, S.D. (AP) — U.S. Senate candidate Larry Pressler has filed a brief in federal court in support of couples that are seeking to repeal the state's ban on same-sex marriage.

Six South Dakota couples filed a federal lawsuit challenging South Dakota's ban last month. The federal complaint filed in Sioux Falls challenges a law and voter-approved constitutional amendment.

Pressler filed the brief with the court Wednesday. He says he filed a similar document with the U.S. Supreme Court a few years ago also in support of the issue.

Attorney General Marty Jackley has said he's obligated by law to defend the ban.

Pressler will be on the November ballot seeking the seat being vacated by retiring Democratic Sen. Tim Johnson.