The tricky political topography of same-sex marriage

The advocacy group, Australian Marriage Equality, commissioned a national poll of 1,050 voters by Galaxy Research in October.

After being told same sex marriage was legal in countries like Canada, the Netherlands, Norway and parts of the United States, voters were asked whether they agreed or disagreed that same sex couples in Australia should be allowed to marry: 62 per cent agreed, 33 per cent disagreed and five per cent were undecided.

But Labor's problem is that even if a national majority of voters favours reform, the issue threatens to widen an already-problematic cleavage in its electoral base: the divide between the ALP's traditional working class supporters in the outer suburbs and regional areas, who are concerned with bread and butter economic issues, and its newer demographic of voters in the inner cities, more focussed on a socially-progressive values agenda.

We can flesh out the political geography of community attitudes towards gays a little more by delving into the pollster Roy Morgan Research's Single Source survey data.

Dig beneath these national-level responses and there is significant divergence in attitudes to gays in different parts of the country - which is one of the factors influencing the stance of the major political parties.

Morgan's Single Source comes from face-to-face surveys carried out each week with around 1,400 people aged 14 and over.

The surveys typically reach more than 50,000 different people a year and, among other things, ask them if they believe homosexuality is immoral and whether gay couples should be allowed to adopt children. The chart shows the nationwide responses to these two questions in surveys carried out over the last 12 years.

As Morgan's chief executive Michele Levine says: ''Over time Australia is becoming more socially-progressive on a whole range of issues. Across the board, we are becoming more open-minded on these socio-sexual issues.''

But dig beneath these national-level responses and there is significant divergence in attitudes to gays in different parts of the country - which is one of the factors influencing the stance of the major political parties.

Morgan's numbers for the last two years can be sliced and diced to give results for statistically representative samples of people from each of the 150 federal electorates. In Bandt's electorate of Melbourne, for instance, they show 71 per cent of people say gay couples should be allowed to adopt; in the country Victorian electorate of Mallee, by contrast, 70 per cent say gays should not adopt.

In Capricornia, in Queensland's north, 45 per cent of people believe homosexuality is immoral; in the inner-city electorate of Sydney, only 9 per cent see homosexuality as immoral.

The electorate-by-electorate responses to both of Morgan's questions suggest anti-gay sentiment is concentrated in the following areas:

• pretty much everywhere in regional Queensland;

• several country electorates in NSW (Cowper, New England, Paterson, Lyne and Hume), Victoria (Mallee), South Australia (Grey and Barker) and Western Australia (O'Connor) held by the Coalition and independents;

• traditional Labor seats in Sydney's west (Blaxland, Chifley and McMahon) and south-west (Barton, Banks and Watson);

• pockets of Melbourne's south-eastern suburbs (Labor's Hotham and Bruce);

• and northern Tasmania (Labor's Bass and Lyons).

By contrast, the areas with the most positive attitudes towards gays are:

• inner-city electorates which are mainly Labor but under threat from the Greens (Sydney, Melbourne, Brisbane, Adelaide, Melbourne Ports, Grayndler and Denison);

• affluent Liberal seats in the two big capitals (Malcolm Turnbull's Wentworth, Joe Hockey's North Sydney, Tony Abbott's Warringah and Bradfield in Sydney and Kooyong, Higgins and Goldstein in Melbourne);

• regional areas with exposure to the sea-change/tree-change demographic and the gay dollar (McEwen, Ballarat, Newcastle and Richmond);

• suburbs in Melbourne's north (Labor's Batman, Wills and Jagajaga), outer east (the Liberals' Casey) and outer south-east (Labor's Isaacs).

To see how all 150 electorates lined up, click here and here.

Morgan's Levine says these differences of opinion on homosexuality reflect underlying demographic divergences around the country.

''Areas that are better educated, more socially aware, more progressive in attitudes towards technology, a cosmopolitan society - all of these things go together and are fairly predictably associated with more liberal attitudes on sexual issues,'' she said.

''Then the areas where you have people who are very socially-conservative are generally the areas where people say things like 'the world was better when I was growing up, things are changing too fast'.''

What does this variation mean when it comes to the marginal seats which decide elections?

Of the 30 electorates with the highest levels of anti-gay sentiment, 23 are safe seats and seven are marginals (Labor's Capricornia, Banks and Petrie and the Coalition's Dawson, Longman and Fisher).

The next chart compares marginal and safe seats on the spectrum running from places where very few people think gays are immoral to those where more than a third of the electorate have a moral objection to homosexuality.

It turns out the marginals are more clustered in the middle of the spectrum of opinion while the distribution of safe seats is more skewed towards the anti-gay end. So perhaps the marginal seats are not as fussed by gay marriage as the politicians think.

Mark Davis is the national editor for The Age and The Sydney Morning Herald.