After the New York State Legislature voted in June to allow gay couples to wed, opposition groups vowed that they would make trouble for lawmakers who supported the marriage bill the next time they had to face the voters.

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.

Brian S. Brown, the president of the National Organization for Marriage, said in a telephone interview that the group planned to spend more money, about $30,000, on automated phone calls, additional mailings and get-out-the-vote efforts before the election, scheduled for Tuesday.

“David Weprin made a terrible mistake when he voted for same-gender marriage,” Mr. Brown said, “and I think his community is going to hold him accountable.”

READ MORE NY TIMES