With the proposed legislation due to go before parliament at the end of this month
With the proposed legislation due to go before parliament at the end of this month, opponents travelled from all over France for a demonstration on Sunday supported by leaders of the mainstream centre-right opposition, the Catholic church and France's five-million-strong Muslim community.
Organisers of the "demo for all" (a reference to the government's billing of its legislation as "marriage for all") were hoping for a turnout running into six figures in the hope of putting pressure on President François Hollande to change his mind, or at least agree to review the plans.
Hollande has made it clear he has no intention of dropping a promise he made in his election manifesto last year and is already pencilled in to attend one of France's first gay marriages once the legislation is enacted later this year.
Despite months of protests, opinion polls have shown consistently that most voters support the right of homosexual couples to marry and a narrower majority favour adoption rights being enshrined in law.
The slim prospect of success did not appear to dampen the spirits of the protesters however as giant marches converged near the Eiffel Tower after setting off from three different starting points.
Many of the protesters were accompanied by children, some of who brandished placards exclaiming: "Born of a man and a woman." A more light-hearted banner proclaimed: "There are no eggs in the testicles."
Movement against gay marriage
Jacques Julien (70), who had travelled from the Haute-Loire region of central France, said he had voted for Hollande but disagreed with the Socialist president's approach.
"A man and a woman, that is the basis of the family," he said. "I'm saying out loud what many people on the left think privately."
The movement against gay marriage has given France a new celebrity in the form of its public face, Virginie Tellenne, a Parisian socialite who goes by the name of Frigide Barjot.
Her assumed name – a play on the name of French film star Brigitte Bardot, a sex symbol in the 1960s – translates as Frigid Loony.
"The president must listen to us," Barjot said on Sunday. "He must put this law on hold."
Among those who took part in Sunday's protest was Jean-François Copé, the leader of the centre-right UMP party.
"This is an important test for Francois Hollande because you can see very clearly that there are millions of French people who are very concerned about this reform," Cope said. – Sapa-AFP