The niece of anti-gay marriage Front National leader Marine Le Pen has “guaranteed” that same-sex marriage would be repealed if she wins the Presidential election.

Marion Maréchal-Le Pen is the granddaughter of Front National (FN) founder Jean-Marie Le Pen and the niece of the far-right party’s current leader Marine Le Pen.

She was elected in 2012 at age 22, the youngest MP in France’s political history.

Maréchal-Le Pen, who last year said that same-sex marriage would “open the door to polygamy”, has made the guarantee that her aunt, who is through to a Presidential run-off, would repeal same-sex marriage if she is elected.

“It will not be the first priority, but … [repealing gay marriage] is a promise that we will stick to, and I will personally guarantee that this bill is demolished,” the MP for Vaucluse told BFMTV.

Far-right French politician Marine Le Pen, who suggested she would temporarily step aside as the leader of the party last week, had already pledged to repeal same-sex marriage.

The number 87 proposal for Le Pen’s candidacy says same-sex marriage will be repealed.

“The Front National will replace the provisions made under the Taubira law [the bill enabling people of the same sex to wed, named after Justice Minister Christine Taubira] with civil unions,” it reads.

The candidate came second in the first round of voting last month and will face Emmanuel Macron – the centrist, pro-equality candidate – in the second and final vote on May 7.

One group of people who helped put Le Pen through to the second round is gay men, who voted National Front in bigger numbers than ever before.

One in five gay men said they intended to vote for Le Pen when polled ahead of the first round of voting.

Maréchal-Le Pen last year said that she thought same-sex marriage would lead to the legalisation of polygamous marriages.

Le Pen faces an uphill battle – she is currently polling at 38% to Macron’s 62% in the run-off.

But if she does pull of an extraordinary victory in the fifth republic, it could well be the votes of white gay men that pushed her over the finish line.