COLUMBUS, Ohio (AP) — The lead plaintiff in the landmark lawsuit that led to legal gay marriage nationwide is endorsing the Democratic challenger to Ohio senator Rob Portman, despite Portman's dramatic position reversal in favor of same-sex unions.

James Obergefell (OH'-burk-uh-fel) told The Associated Press Monday he's backing ex-Ohio Gov. Ted Strickland in next year's closely watched U.S. Senate contest.

Obergefell said he appreciates Portman's support for marriage equality but disagrees with Portman on the issue being decided state-by-state. He said Strickland and the Democrats also align with him on other issues such as opposing gay-conversion therapy.

Strickland must win his party's nomination to face Portman, who alienated some conservatives with his 2014 decision to support gay marriage after learning a son is gay.

Portman's campaign said he's still the better candidate for Ohio.