The National Organization for Marriage (NOM) on Monday pledged $500,000 to defeat Minnesota GOP lawmakers who vote to legalize gay marriage in the state.

NOM, which contributed more than $2 million to last year's unsuccessful campaign to put an amendment in the Minnesota Constitution defining marriage as a heterosexual union, has helped fund primary challengers against Republicans in other states who voted for marriage equality.

The announcement comes days after Senator Branden Petersen spoke out in support of a marriage bill expected to be introduced shortly.

“Republicans like Branden Petersen don't realize that not only is voting to redefine marriage a terrible policy, it is also a career-ending vote for a Republican,” NOM President Brian Brown said in a statement. “NOM will do everything in our power to defeat any Republican who votes in favor of same-sex marriage.”

In remarks to the Pioneer Press, Petersen said his vote was not for sale.

“Whether it's $500,000 or $50 million, my vote is not going to be bought either way,” he said. “I'm going to do what's right.”

Pointing to New York, Brown said his group would not hesitate to take action.

“Legislators need look no further than what happened to GOP senators in New York,” Brown continued. “Four of them were responsible for passing gay marriage. We helped take out three of those senators by repeatedly informing their constituents of their betrayal on marriage. They are now out of office. We will not hesitate to do the same thing in Minnesota.”

“Marriage is not a partisan issue, and NOM does not hesitate to oppose weak Republicans and support strong Democrats.”