Rupert Cornwell: Three more states back gay marriage, but will Obama?

Out of America: The issue is still bitterly divisive, especially in the conservative heartlands, but there are clear signs that the country's attitudes to gays are changing

It hasn't been formally designated as such, but so far this is America's year of gay rights. The signs are many and various. Sean Penn won this year's Oscar for best male actor with his brilliant portrayal of Harvey Milk, the first openly gay man elected to political office in the US. Since January, the country has had a president who describes himself as a "fierce advocate of equality for gays and lesbians". And most remarkable of all, within the past few weeks three more US states have legalised same-sex marriage.

Do not misunderstand me. America is not about to turn into the social conservative's vision of hell, where marijuana is available in diners, an abortion clinic stands on every corner and old-fashioned Christian marriage is about to vanish from the Earth. Indeed, it is far from certain that these limited successes for gay marriage will endure.

The issue is bitterly divisive: witness the $1.5m "Gathering Storm" TV ad campaign by a group called National Organisation for Marriage, that portrays same-sex marriage as a mortal threat to religious freedom – or the plight of the current Miss California, Carrie Prejean, who last month may have lost her chance to become Miss USA 2009 by speaking out against gay marriage. The new laws could be reversed, either by the courts or by popular referendum. But something is changing, and not just attitudes. The controversy over gay marriage is no longer simply a social or "values" issue. Increasingly it is seen as a matter of basic civil rights.

America is well known as a Christian and heavily church-going land. Ask its citizens if they approve of same-sex marriage and on religious grounds alone a majority would probably say no (even people such as President Obama who are in favour of civil unions). But ask them whether they believe that gay people should have the same rights as everyone else, and a majority, I would wager, will say yes.

By international standards, America is no trailblazer on gay rights. Right now, same-sex marriage is sanctioned by seven countries (five in Western Europe, starting with the Netherlands in 2001, as well as Canada and South Africa), while two dozen others, including Britain, recognise civil unions or something similar, giving a gay couple some or all of the legal rights and responsibilities enjoyed by heterosexual marriage partners.

In the US, only five of the 50 states have legalised same-sex marriage, with New Hampshire perhaps about to become the sixth. For a few months last year, California too was in their number, until last November's Proposition 8 referendum, in which voters overturned a ruling by the state's Supreme Court that had permitted gay marriage. Even so, the cause is making progress.

From the outset, the liberal North-east and the laid-back West Coast looked the most promising territory, and so it has proved. Apart from California, the first three states to ratify same-sex marriage – Massachusetts, Connecticut and Vermont – were in New England, and this week they were joined by a fourth, Maine. If, as seems likely, New Hampshire soon follows suit, then tiny Rhode Island will be the only New England hold-out.

Meanwhile, New Jersey and Washington DC allow civil unions, while New York and the capital recognise same-sex marriages from other states. The other three states that have endorsed civil unions are the Pacific coast trio of Oregon, Washington and California. All of the aforementioned, it goes without saying, are reliably Democratic.

But now the conservative heartland is starting to waver. Last month Iowa, hitherto best known for pig farms, political caucuses and the sentimental baseball movie Field of Dreams, became the first midwestern state to legalise gay marriage. Yes, the same Iowa that in 2004 voted for the re-election of George Bush. Conservatives shudder to think: where will it all end?

No one expressed the changing attitudes better than Maine's Democratic governor. John Balducci is a Catholic who had previously supported civil unions but opposed gay marriage: "It's not the way I was raised, and it's not the way that I am."

But, he noted as he signed the bill into law, it did not force any church to recognise a marriage, or perform a ceremony, with which it disagreed. Rather, "this is a question of fairness and equal protection under the law, and ... a civil union is not equal to a civil marriage". So much for the argument that the dispute is one of semantics, that civil union is marriage by another name, and the insistence by the gay lobby on the word "marriage" is not worth the fuss.

And soon Obama himself may not be able to ignore the fuss. Thus far, the White House has managed to avoid being drawn into the controversy, maintaining that gay marriage is a matter for individual states to decide. But inevitably the focus is switching to the federal level as well, as activists demand the repeal of the Defence of Marriage Act passed by Congress in 1996 but opposed by Obama, which barred the federal government from recognising gay marriages and removed from one state any obligation to recognise a gay marriage conducted in another.

Obama has every reason to tread carefully. Back in 1993 Bill Clinton got off to a terrible start as president when he chose to wade into the gays-in-the-military controversy. His successor but one already has enough on his plate. If he espouses the gay marriage cause he risks losing centrist support and creating exactly the sort of distraction that cost Clinton so dear. The same goes if Obama bows to the pressure of activists and appoints a first openly gay justice to fill the impending vacancy on the Supreme Court.

For the moment, though, these issues seem prepared to wait – as well they might. Not only does Obama like to play the long game. If gay marriage is indeed turning into a civil rights struggle, history's lesson is that such struggles take decades to win.