Groups of supporters and opponents of equal marriage began to head for the House in Minnesota, as it gears up for today’s vote on a measure to legalise it.

Advocates of the measure have voiced hopes that the state will become the twelfth in the US to legally recognise same-sex marriage.

The Associated Press reports that supporters of the measure had begun to descend on the Capitol this morning. The House will vote on a measure to legalise equal marriage at 1pm, local time.

CBS Local also reported that opponents to the bill expected more than a thousand protesters to turn up, and that its supporters expected equally as large a turnout.

Opponents had already begun to hold up signs saying “vote no”, outside the House.

Minnesota could be the next US state to legalise equal marriage, as its Democratic-controlled House will vote on a measure to legalise it on Thursday, a possible signal that its advocates have gathered enough votes for it to pass.

House Speaker Paul Thissen had said he would not schedule a vote on the bill until he knew it had the necessary 68 votes to pass.

Both those in support and opposition to equal marriage have been putting increasing pressure on lawmakers to publicly reveal which way they intend to vote on the measure.

Minnesota State Senate members on the Judiciary Committee, as well as the Civil Law Committee in the House, in March passed the equal marriage bill.

After hearing almost three hours of testimony, the Senate committee passed the bill 5 votes to 3, along party lines, and the House committee voted voted 10 to 7 for the bill.

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. 

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

On 6 November, 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.