The US state of Minnesota could soon become the twelfth to legalise equal marriage, as on Monday its Senate will vote on a measure to legalise it.

Leaders in the Senate have also already said they had already gathered enough votes to pass the bill.

If the bill passes in the Senate on Monday, Democratic Governor Mark Dayton could sign it into law as early as next week, and same-sex weddings could begin to take place in August.

The House of Representatives in the US state of Minnesota passed a bill to legalise equal marriage on Thursday, with a clear majority in favour.

The final vote was 75 to 59, following a two-hour debate around the issue. It will now move to the Senate, which will take up the issue on Monday.

Among the opposition was Republican Representative Peggy Scott, who said she was brought to tears by the prospect of same-sex couples being allowed to marry.

Leading up to the vote, thousands of supporters and opponents of equal marriage gathered outside the House. During the debate, opponents to the measure argued that it was “not the time” for the measure, but its proponents denied they were “destroying” marriage, and said they were to “uphold it for all”.

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.