The head of the union, which has 2.4 million members, said in an interview that he would not be urging a vote for the SPD as IG Metall did in 2005 for former chancellor Gerhard Schroeder.

"I know that relations between the SPD and the union have historically been very strong, but we are now in the 21st century. The time when the unions can say 'vote for this person or that person' is over," Berthold Huber told the Sueddeutsche Zeitung.

"People can think for themselves," he added.

Huber's comments represent the latest setback in what has been a very challenging week for SPD leader Frank-Walter Steinmeier, who is seeking to topple Merkel in September 27 elections.

Steinmeier, foreign minister in Germany's governing coalition, has seen his party lag more than 15 points behind Merkel's conservatives in the polls and his personal popularity is 37 points behind the high-flying chancellor.

Steinmeier also lost a key ally to a political scandal when Health Minister Ulla Schmidt was forced to pull out of his campaign team after she took her official car with her on holiday at public expense, prompting a public outcry.

Steinmeier presented his shadow cabinet Thursday in a bid to kick-start his party's campaign at a time when the SPD is suffering from scandals and a lack of public faith.

But despite the Ulla Schmidt scandal and other body blows the SPD have suffered of late, Steinmeier maintained that the outcome of the general election is anything but a foregone conclusion as he revealed his mixed team of current ministers and a few new faces that lots of ordinary Germans may never have seen before.

Steinmeier confident of recovery ahead of election

"I'm convinced that we have better people and better ideas than our political opponents," he said at the official unveiling in Berlin. "The remaining two months until the general election will show that I'm right. We'll be making clear that we're better prepared to shape the future of our country. And make no mistake, without the SPD in government this country will see a sharp decline in social policies."

Schmidt's "Car-gate" scandal weighs heavily on the SPD

In what could be a telling omission, Steinmeier's team doesn't include health minister Ulla Schmidt - at least not for now. But should the federal audit agency clear her of accusations that she allegedly wasted taxpayers' money during her vacation, she may be brought in later.

Many names of the shadow cabinet members are hardly known to the public, such as Ulrike Merten, who would be the first woman to become defense minister in Germany.

Steinmeier isn't the only Social Democrat to get the election buzz from Thursday's cabinet unveiling. SPD campaign manager Kajo Wasserhoevel insists that the Social Democrats are a unique force in Germany. According to Wasserhoevel, the SPD are not only unlike the Left Party, the other albeit more radical socialist alternative, but they are also very different from the bloc of conservatives with whom they currently share government.

Conservatives accused of failing on economy, social justice

"The essential question for us is whether the financial crisis and the mistakes that were made in the banking sector here will lead to any major changes and more efficient control mechanisms," Wasserhoevel said. "With the Christian Democrats, one crisis just leads to another or so it seems.

Wasserhoevel is charged with steering the SPD campaign

"On the social justice front, we'll continue to fight for the introduction of a minimum wage across all sectors of the economy," he added. "These are the things that people are taking a big interest in. And if our campaign helps to make clear what we Social Democrats stand for, we'll be able to win back many votes."

However, most political observers expect that the election in September will largely be influenced once again by the charisma (or lack of it) of the top candidates. Many doubt that SPD challenger Steinmeier has what it takes, while others believe he would be a breath of fresh air.

Author: Hardy Graupner (nda)

Editor: Neil King