Germany's foreign minister has been backed to become his country's next president, despite once referring to Donald Trump as a 'hate preacher'.

Frank-Walter Steinmeier, a 60-year-old Social Democrat, will take over the largely ceremonial role as head of state from Joachim Gauck, whose five-year term ends in February.

While normally studiously diplomatic, Steinmeier strongly criticised US President-elect Donald Trump during the American election campaign.

German Foreign Minister Frank-Walter Steinmeier is pictured waving as he arrives for talks with Polish Foreign Minister Witold Waszczykowski, in Warsaw earlier this year

Asked in August about the rise of right-wing populism around the world, Steinmeier targeted those who 'make politics with fear'.

He cited supporters of Brexit, the nationalist Alternative for Germany party, promoters of Britain's exit from the European Union, and 'the hate preachers, like Donald Trump at the moment in the United States.'

Following Trump's election, Steinmeier said the Republican's victory meant 'nothing is going to get easier. A lot will get harder.'

He said Germany would seek dialogue with the Trump administration, but warned that American foreign policy would likely become 'less predictable.'

German news agency DPA said today Chancellor Angela Merkel's ruling Christian Democrat party would back Steinmeier's nomination for the post.

Together with the votes of Steinmeier's own SPD party the 60-year-old political veteran would likely have enough support to win a vote among the 1,260 delegates who elect Germany's next president on Feb. 12.

Steinmeier (left) with German Chancellor Angela Merkel, right, at a cabinet meeting last year. They are expected to work comfortably with each other desperate being in rival parties

A veteran of the German political system and a familiar face in world capitals, Steinmeier served as Merkel's vice-chancellor and chief diplomat during her first 'grand coalition' government in 2005-2009.

In his second stint as foreign minister beginning in 2013, he has at times drawn fire for attempting to keep the lines of communications open with Russia despite deteriorating relations over Ukraine.

While his Social Democrats have praised his approach as in keeping with their long tradition of Ostpolitik, critics have accused him of being a 'Russlandversteher', or apologist for Russia.

German Foreign Minister Frank-Walter Steinmeier, left, and his wife Elke Buedenbender arrive for an official state dinner with the Queen in Berlin last year

Allies raised eyebrows in June this year when he warned Nato against 'sabre-rattling and warmongering' after it conducted military exercises in eastern Europe in response to the perceived threat posed by Russia.

But SPD leader Sigmar Gabriel said Steinmeier had earned widespread respect and the necessary trust required to fill the post.

Steinmeier first gained national attention in 1998 when he became chief of staff to Merkel's predecessor, Gerhard Schroeder.

Steinmeier (right) will succeed 76-year-old Joachim Gauck (left) when he steps down from the job in February

He was credited with keeping a sometimes chaotic centre-left government running smoothly and seeing through a package of economic reforms and welfare-state cuts in 2003.

The reforms, launched at a time of high unemployment and economic stagnation, were credited with helping fuel growth and make the economy more resilient, but critics said they fuelled social divisions.

He won widespread respect in 2010 when he took a few weeks away from politics to donate a kidney to his wife, Elke Buedenbender, a judge at a Berlin administrative court.

Steinmeier's promotion would leave a void in the foreign ministry, where he led efforts to resolve conflicts in Ukraine and Syria.