The SPD's North Rhine-Westphalia branch voted last week to expel Wolfgang Clement, a heavyweight centrist figure and former state premier and prominent minister at federal level, for "breaching party solidarity."

Confident of support on the right wing of the traditional party of the German centre-left, Clement is resolutely refusing to back down and is fighting the ruling.

On the surface, the battle is about strong personalities and the inevitable conflict between the right to express opinions freely and the need for party discipline.

But in reality, a classic "Richtungsstreit" -- an ideological struggle over the party's political direction -- has erupted.

The timing is awkward. The SPD is hoping to make a large dent in the majority enjoyed by the conservative Christian Social Union (CSU) in the Bavarian state election on September 28.

Before the Clement affair broke out into the open, opinion polls suggested the CSU was likely to lose the absolute majority it has enjoyed in the large southern state since 1962, with the SPD the major benefactor.

Clement ignites in-party quarrel

Clement outraged the party with his comments before another state election, in Hesse, when he came close to warning against a vote for SPD leader Andrea Ypsilanti on the grounds of her opposition to both nuclear and coal-fired power generation.

"Consider carefully and vote carefully on who should be entrusted with responsibility for the state," he wrote just a week before the Jan. 27 poll.

Many in the SPD blame Clement for the inconclusive outcome which left a caretaker government headed by the Christian Democratic Union (CDU) in control in Hesse.

Party members were quick to point out that he had left politics at the end of 2005 for a career in industry -- sitting on the board of the major electricity company RWE Power.

SPD leaders at federal level are desperately trying to calm the situation.

"Our aim is to build bridges in this conflict," party general secretary Hubertus Heil said, while SPD federal chairman Kurt Beck called for Clement's life-long service to the party to be recognized.

Party figures against Clement

But the conflicting parties were more interested in digging trenches than building bridges.

Axel Schaefer, a member of parliament for Bochum, the Ruhr town where Clement is registered with the SPD, urged the outspoken 68-year-old to go.

"One constantly hears 'me, me, me' from Clement, when we would like to hear 'we' for a change," Schaefer told local daily Westdeutsche Allgemeine Zeitung.

SPD North Rhine-Westphalia deputy chairman Jochen Ott labelled Clement "arrogant" and urged him to accept that he could not continue to undermine the party, "otherwise he should go of his own accord."

And SPD Bavarian chairman Franz Maget, with his eye fixed on next month's election, said that, while Clement was an "upstanding Social Democrat, he is also boneheaded."

Maget called for the former economics and labor minister to accept a formal rebuke from the party and to agree to maintain party discipline.

Clement made clear that nothing was further from his mind. "What they are demanding is a muzzle, even in the event that SPD leaders somewhere join forces with the Left Party, and I won't be part of it," he told national public broadcaster ZDF.

Clement once again had Ypsilanti in his sights. The Hesse SPD leader this week put out feelers to the socialist Left in the state in the hope of forming a minority coalition with the Greens based on the tacit support of the Left.

SPD presented with problem from the Left

How to confront the apparently inexorable rise of the new party with its roots in formerly communist East Germany lies at the heart of the struggle.

The SPD, whose roots go back to the mid 19th century labor movement, has plumbed all-time lows in opinion polls this year.

The Left has eaten steadily into its traditional support base, even in western states -- like North Rhine-Westphalia and Hesse -- where the SPD had previously felt secure.

A poll published Wednesday said national support had fallen to a new all-time low of 20 percent after the North Rhine-Westphalia ruling.

The relationship with the Left is at the core of the SPD's problems as the party enters the last year of an unwieldy "grand coalition" at federal level headed by CDU Chancellor Angela Merkel.

Currently, the SPD shuns The Left in western states and at federal level, although it has entered into a coalition with the party in the city-state of Berlin.

Beck has not helped matters by appearing to switch course two or three times over whether to accept the backing of the Left in Hesse.

Clement stands firm against deal with the Left

Clement has now charted a clear course rejecting any kind of deal with the socialists, and he has the backing of many within his party, as another SPD veteran, former Hamburg mayor Klaus von Dohnanyi, has made clear.

"It would be a big mistake to expel Clement. He's not alone within the SPD in taking this position," the party heavyweight said.