The campaign against the French Government’s plans to legalise same-sex marriage has gathered momentum in the last few weeks, with Catholic bishops and opposition politicians leading the way.

Opinion polls published last week and at the weekend suggest there has been a significant fall in public support for the proposal.

Surveys by the Ifop polling group show support for gay marriage has weakened from 65 percent in August to 61 percent now as the public debate has taken off.

Support for full adoption and assisted procreation rights for gay couples has slid from 53 per cent to 48 percent now.

And a BVA survey published by Le Parisien newspaper on Saturday said this was the first fall in support after a decade of rising acceptance for the two reforms. “Opinion trends on the subject are clearly on the retreat,” it said.

The drop in support comes as the Socialist Government prepares to publish draft legislation approving same-sex marriage.

The Archbishop of Paris, Andre Cardinal Vingt-Trois, called on Catholics to demonstrate their opposition to the proposal by writing and speaking to their elected officials or taking part in protest marches.

He made the call at the annual plenary meeting of the country’s Catholic bishops.

Cardinal Vingt Trois said that the presidential and legislative elections which took place earlier this year did not give the Government carte blanche, “especially not for reforms that very profoundly affect the equilibrium of our society”.

“It will not be ‘marriage for all’,” he said, citing the slogan of the pro-reform campaign, “it will be the marriage of a few imposed on all”.

Socialist Party politicians hit back at the Cardinal on Sunday for his remarks.

“I’m shocked by this attitude which I think is a kind of return to a fundamentalism that I find problematic,” Jean-Marie Le Guen, Socialist senator from Paris, said of Vingt-Trois’s speech to bishops in the pilgrimage town of Lourdes.

Party spokesman David Assouline said it was not the Church’s role “to oppose the will of the legislature, especially concerning civil marriage in a secular republic.”

However, Laurent Wasquiez, a leading deputy in the conservative opposition UMP party, defended the Cardinal’s criticisms and called on the government to take more time to seek a consensus about any change in the definition of marriage.

“The government wants to rush this through, without taking the time to get everyone around the table,” he told France 3 television.

Jean-Francois Cope, a contender for the leadership of the main opposition party, the centre-right UMP has backed proposals for a large national protest march in defense of traditional marriage.

Protesters took to the streets of 75 cities and towns across France last week and lay Catholic leaders have called for another round of demonstrations in mid-November. Sample letters against the law have been posted on websites sent to elected officials.

Mr Hollande’s government had wanted to push the change through quickly, but significant opposition from Christian, Muslim and Jewish leaders has slowed the process.

Religious leaders have avoided religious arguments and framed the debate as not one of gay rights but about the social and psychological changes the reform would make for families, especially for children of gay couples.

Mayors around the country have formed groups to pledge to preside at same-sex marriages if they are legalised or to demand a “conscience clause” to opt out of doing so.