CAMPAIGNERS seeking to block legalisation of same-sex marriage in Scotland face a seemingly impossible task, according to the latest evidence.

The Equality Network charity, which runs the Equal Marriage campaign in favour of legislation to allow same-sex marriages, cites a raft of polling evidence from recent years showing public support running at more than two to one in favour of reform.

But it is on the floor of the Scottish Parliament where the issue will be decided, and the group claims the latest figures are stacking up heavily in favour of those who back the change.

There are now 89 MSPs who have stated their support for the bill to make the change published at Holyrood last week, including all Cabinet ministers, the leaders of each of the four parties and every Liberal Democrat MSP.

Only 11 MSPs have publicly stated their opposition, so even if all of the 29 MSPs who are so far publicly undeclared voted against it, the bill would still be backed by a majority of more than two to one.

Those who have declared their opposition to same-sex marriage tend to have personal faith-based reasons for holding socially conservative views, or represent constituencies where such views are widely held.

Two are SNP MSPs representing Skye and the Western Isles, where there are strong Kirk and Free Church opinions. One is a Labour MSP representing a central-belt seat with a large number of Catholics, and seven are Conservatives scattered across the country. Independent Bill Walker, elected as an SNP MSP but forced to quit the party whip when he faced domestic abuse allegations, also opposes the change.

Despite the figures, campaign group Scotland for Marriage vowed last week to step up its fight, saying: "We now have activists present in every one of the 73 Holyrood constituencies throughout the country and we will actively target individual MSPs using local voters to urge them to vote against changes in the law.

"They will pile increased pressure on the politicians who are answerable to them at the ballot box, visiting their surgeries and holding demonstrations outside their constituency offices. MSPs will be reminded in no uncertain terms the implications they face if they vote against the views of the majority."

Westminster political leaders wrote messages of support for same-sex marriage in the programme for the Pride London parade at the weekend. Prime Minister David Cameron said: "There will be girls and boys in school today who are worried about being bullied and concerned about what society thinks of them because they are gay or lesbian.

"By making this change they will be able to see that Parliament believes their love is the same as anyone else's love and that we believe in equality."

Deputy Prime Minister Nick Clegg wrote: "Many straight people have argued for the reform with as much passion as gay people. Why? Because this isn't just about technical changes or legal definitions. It isn't just a 'gay issue'. It's about the kind of society we wish to be."

Labour leader Ed Miliband said: "Too many young people still fear to come out at school due to bullying. In too many places in the world, it is still a crime to be gay."

The MSPs who will vote against same-sex marriage

SNP

Alasdair Allan Na h-Eileanan an Iar

Dave Thomson Skye

Labour

Elaine Smith Coatbridge and Chryston

Conservative

Alex Fergusson Galloway and West Dumfries

Murdo Fraser Mid Scotland and Fife

Alex Johnstone North East Scotland

David McLetchie Lothian

Nanette Milne North East Scotland

Margaret Mitchell Central Scotland

Elizabeth Smith Mid Scotland and Fife Independent

Bill Walker Dunfermline