Trial attorney Ted Olson will attend a rally against passage of a proposed constitutional amendment which would define marriage as a heterosexual union in North Carolina.

Voters will decide on the measure during the state's May 8 presidential primary.

If approved, the amendment would bar North Carolina from recognizing the relationships of gay and lesbian couples with marriage, civil unions and possibly domestic partnerships.

The 71-year-old Olson, a prominent Republican, shocked conservatives in 2009 when he joined the legal team challenging the constitutionality of California's gay marriage ban, Proposition 8.

“I'm going to go down to North Carolina in April,” Olson told LGBT | POV, a blog hosted by Frontiers in LA. “There's a big rally down there. I'm going to go down and do my bit.”

Referring to testimony heard during the 2010 trial, Olson said he was looking forward to the first defeat of such an amendment.

“We want to win one. You heard the witness talk about how the outcome [of anti-gay ballot measures] is always against gay and lesbian people. It would be really great if we started changing that. And maybe North Carolina is a chance.”

The April 1 rally will be held in Greensboro and is being organized by the group Faith Against Amendment One, a coalition member of Protect All North Carolina Families.

(Related: Majority oppose North Carolina gay marriage ban.)