(Getty)

The chairman of the leading opposition party in Germany has promised to push through marriage equality this week.

Martin Schulz, who heads the centre-left Social Democratic Party (SPD), tweeted this morning to say in German and English: “We will push through marriage equality in Germany. This week.”

He added to Associated Press: “Angela Merkel made…a move yesterday and we are taking her at her word.”

Her “change of heart…should be concluded this week,” he continued.

It is understood that this means Schulz is promising to attain a parliamentary vote on the subject before parliament closes on Friday.

The SPD is currently the junior partner in a grand coalition with Chancellor Angela Merkel’s right-wing Christian Democrats.

The bold pledge came after Chancellor Merkel said yesterday she could see envision parliament making a “decision of conscience” on the issue.

This would entail a free vote, rather than politicians being forced to vote along party lines.

The Chancellor has softened her stance ahead of September’s federal election, after all of

her potential coalition partners – including the SPD, the Greens and the Left Party – made same-sex marriage a condition of coalition.

Merkel’s party, which remains opposed to equal marriage, maintains a significant lead in the polls, but is unlikely to gain enough seats to govern alone.

Across three terms in power, the long-serving Chancellor has always relied on coalitions with either the SPD or the liberal Free Democratic Party.

Merkel has previously rebuffed calls to introduce same-sex marriage, saying: “For me, marriage is a man and a woman living together.”

But earlier this year, a survey found that an overwhelming majority of Germans support same-sex marriage.

The poll, conducted by survey company Emnid for Sunday newspaper Bild am Sonntag, revealed that 75 percent of Germans favour full legal equality for gay people in life partnerships.

Unlike the Bundestag (main chamber of the Germany Parliament), where Chancellor Merkel’s Grand Coalition holds control, the Bundesrat (equivalent to the Upper House/Senate) is controlled by the 16 state governments, with a left-wing majority.

A coalition of the Social Democrats, the Greens and the Left backed a bill in the Bundesrat that would recognise unions between same-sex couples, despite Chancellor Merkel’s insistence it is between a man and a woman.

However, no legislation is likely to pass the Bundestag without the government’s blessing.

Germany already allows same-sex couples to enter into registered life partnerships that provide some of the benefits of marriage.