Berlin - Germany's Social Democratic Party (SPD) gathered Saturday to anoint Frank-Walter Steinmeier, 52, the German foreign minister, as its candidate to challenge Chancellor Angela Merkel in the general election next year.

The party was also to appoint a new national chairman, Franz Muentefering, 68.

Both men were the national committee's sole nominees and face a simple yes-no vote at the one-day national conference in Berlin.

The change follows the resignation six weeks ago of Kurt Beck, a state premier who failed as party leader to boost public support for the centre-left party, which rules Germany in an uncomfortable coalition with Merkel's Christian Democrats (CDU/CSU).

The big parties' weak 2005 showing, with 35 per cent of the votes for the CDU/CSU and 34 per cent for the SPD, forced them into a coalition they hope will become history at the September 27, 2009, polls.

Steinmeier, a grey-haired and bespectacled lawyer, was a longtime aide to former chancellor Gerhard Schroeder and has little electoral experience, but he has enjoyed high personal ratings in public surveys since becoming foreign minister.

The party's dismal rating in opinion surveys - it has not exceeded 27 per cent in Infratest Dimap weekly polls since March - prompted the ouster of Beck.

SPD stalwarts feared Beck, premier of the state of Rhineland Palatinate, lacked the stature and popularity to challenge Merkel at the polls.

Germany's economy is expected to stagnate next year, denying the incumbent parties the benefit of any feel-good factor.

The coalition is expected to become fractious next year as the two parties jostle for position, but feuding between the SPD's left and right wings has eased in recent months as the SPD's star has sunk.

The SPD has been alarmed by the rise of the Left Party, which surged to 13-per-cent national support this week.

The Left is an alliance of disaffected former Social Democrats and easterners with their political roots in the old communist party.

Commentators say the SPD faces a dilemma, since more centrist policies would frighten working-class voters and indirectly aid the Left, whereas more leftist policies or an alliance with the Left Party would frighten centrist voters into Merkel's arms.

The SPD conference, attended by more than 500 delegates, was especially called to appoint the two leaders, not debate new policy.

Key planks in its 2009 election platform are likely to be set next year.

Muentefering, a respected former German labour minister, was party chairman under Schroeder and was recalled by Steinmeier from retirement as a unity figure to take charge as the party cranks up its election campaign.

The decision was taken before Finance Minister Peer Steinbrueck shot to the fore as the most visible Social Democrat in the Merkel government by announcing bank bail-outs and campaigning for stricter world rules on the finance industry.

The SPD has split the roles of national chairman and of candidate for chancellor several times in its history, but the repeated changes in post since 2004 have been unprecedented.

In short succession, the position has been held by Schroeder, Muentefering, Brandenburg Premier Matthias Platzeck and Beck.

Muentefering resigned the post in late 2005 after a dispute with senior SPD officials, but that feud had been forgiven.

Last year he retired from public life to care for his dying wife, Ankepetra, then returned to active politics after her death. (dpa)