On Wednesday, the National Organization for Marriage said it would spend $75,000 to help defeat Assemblyman David I. Weprin, the Democratic candidate in the special election to replace former Representative Anthony D. Weiner.

The organization disclosed in a filing with the Federal Election Commission on Tuesday that it spent $26,000 on direct-mail advertising in opposition to Mr. Weprin, who voted in favor of the marriage bill, and $19,000 in support of his Republican opponent, Bob Turner, who opposes same-sex marriage.