A group opposed to equal marriage in the US state of Minnesota has pledged half a million dollars to defeat any Republican legislator voting to legalise marriage equality in the state.

The National Organization for Marriage (NOM) said it would pay $500,000 (£329,772) to defeat any GOP legislator voting for equality in potential upcoming votes, and woud support any Democrat voting against equal marriage.

In November 2012, Minnesotan voters avoided a constitutional ban on marriage equality, and pro-equality campaigners have since stepped up efforts to push for equal marriage to be legalised. 

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

He went on to threaten that GOP state Senator, Branden Petersen, who last week voiced his intention to vote in favour of legalising equal marriage, would lose out from doing so.

“Republicans like Branden Petersen don’t realise that not only is voting to redefine marriage a terrible policy, it is also a career-ending vote for a Republican,” Brown said, according to the MinnPost. 

“NOM will do everything in our power to defeat any Republican who votes in favor of same-sex marriage. Legislators need look no further than what happened to GOP Senators in New York. 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.”

He went on to urge Democrats to defy party leadership and vote against equal marriage.

He said: ”We urge Democrats in the Minnesota Legislature to vote their values, and not what their party bosses tell them. Standing for true marriage is the right thing to do for Minnesota families, and especially for children. The fact is that Minnesota children, and all children, have a right to expect laws that promote them being raised by a mother and father. We will support those legislators, Democrats and Republicans alike, who vote for Minnesota family values, just as we have done in other states.”

On 6 Novemnber, voters in Minnesota voted ‘no’ on Amendment 1, a constitutional amendment that would have defined marriage as being a union solely between a man and a woman.

WashingtonMaine and Maryland legalised equal marriage in referendums in those states on the same day.