Ed Miliband, the Labour leader, gave his full support to the legalisation of gay marriage as opponents stepped up their resistance to the proposal.
The plan has been greeted with anger and dismay by some church leaders and Conservative MPs – including the head of the Roman Catholic Church in Scotland, who denounced same-sex marriage as an "aberration" – but is being backed by David Cameron and Nick Clegg. Mr Miliband said legislation to bring in civil partnerships for same-sex couples had been a significant step by the last Labour government. He added: "Those equalities now have overwhelming public support and are being copied by many countries around the world. I strongly agree gay and lesbian couples should have an equal right to marry and deserve the same recognition from the state and society as anyone else."
Mr Miliband was speaking as he signed an "equal marriage pledge".
The Government will launch a consultation on equal-marriage legislation next week, intending it to come into force by 2015. The Prime Minister's official spokesman said: "The Government has made clear its commitment to equality. We believe people should have the option of civil marriage, irrespective of sexual orientation."
The Tories and Labour look likely to grant their MPs a free vote on the issue, virtually ensuring the plans will be approved. Cardinal Keith O'Brien, head of the Roman Catholic Church in Scotland, likened gay marriage to the "great wrong" of slavery in a newspaper article over the weekend and launched a fresh attack on the plans yesterday.