Polls in two more US states have found that a majority of voters support equal marriage, as Michigan and Virginia join states with a majority in support.

A poll of 600 Michigan voters run by the Glengariff Group found that 56.8% of voters said they supported equal marriage, a percentage which had risen by 12.5% since a year ago.

The Detroit News attributed the changes to changing Republican attitudes, and noted a stark contrast between the results of the poll and the 2004 voter-approved constitutional amendment banning equal marriage. A poll in 2004 found that only 24% supported equal marriage.

This year’s poll also showed that 90% of voters approved some legal rights for gay couples. “I don’t think I’ve ever seen a policy question move as quickly as this one,” said Richard Czuba, president of Glengariff.

A second poll by the Washington Post found that 56% of voters in Virginia approved equal marriage, a percentage up from 46% two years ago.

Back in 2006, 57% of voters in the state chose to approve a similar constitutional amendment to Michigan, which also banned same-sex marriage in the state.

The Post also attributed the shift to changing Republican views, with 40% in favour of equal marriage. It also noted that the percentage saying equal marriage should be banned had dropped from 86% in 2006 to 47% now.

A Gallup poll released earlier this week found that despite there being 53% of Americans who support legal recognition of equal marriage, two thirds of US citizens hold the perception that overall the US public is opposed to same-sex marriage.

Another poll earlier this week found that over half of voters in the US state of Arizona are also favour of allowing same-sex couples to marry.

The poll found that 55% of Arizonans were in favour of equal marriage, with 35% opposed and 10% were unsure.

Minnesota became the twelfth US state to allow equal marriage, as Governor Mark Dayton on Tuesday signed a bill into law, allowing same-sex unions.

Mr Dayton signed the bill into law on Tuesday at 17:00 local time using eight separate pens. It will allow same-sex weddings to take place from 1 August.

Citing the US Constitution, Mr Dayton said: “The right to liberty certainly includes marrying the one you love.”