By Germany correspondent Caroline Wyatt

Every day, Germany's opposition Christian Democrats must wake up wishing they could turn back the clock to the days when the then CDU leader Helmut Kohl was the undisputed Chancellor of German Unity, ruling the nation for 16 years.

	Reputation at risk The scandal so far The unification chancellor

Instead, they wake up to the awful reality of a party funding scandal which would grace the books of a banana republic - an ex-Chancellor, Mr Kohl, facing criminal investigation over undeclared cash donations and an admission by his anointed heir and successor as leader of the party, Wolfgang Schaueble, that he too had taken a substantial and undeclared cash donation from a dubious source.

The affair began last year with an investigation by the German authorities into a businessman and alleged arms dealer, Karl-Heinz Schreiber, a Candadian-German dual national whom they suspected of non-payment of taxes.

His claims that he had given secret cash donations to the Christian Democrats in their government heyday became public and the scandal rapidly spread.

In a declaration which shook Germany just before Christmas, Mr Kohl admitted that in the 1990s he had taken undeclared cash donations for his party totalling up to two million deutschmarks, which were then hidden in secret bank accounts by the then party treasurer, Walter Leisler Kiep.

Under a law enacted while Mr Kohl was Chancellor, all donations had to be declared - anonymous funding was not allowed.

Mr Kohl and Mr Kiep are both the subject of a criminal investigation - Mr Kohl on allegations of a breach of trust in his handling of his party's financial affairs.

If found guilty, that charge would carry a maximum sentence of up to five years in prison. Yet Mr Kohl is still refusing to name his anonymous donors. He says that he gave them his word of honour to keep their identity secret.

Until this week, Wolfgang Schaeuble was one of Germany's most respected politicians, widely admired for his determination to stay on in politics after he was left semi-paralysed by an assassination attempt.

Despite his closeness to the former Chancellor Helmut Kohl, he promised to get to the bottom of the finance scandal and ensure a full party investigation.

But then - for reasons which have never quite been explained - he too decided to come clean in a German television interview on Monday 10 January.

Mr Schaeuble admitted, almost in passing, that he had also met the businessman at the centre of the affair - Mr Schreiber - at a CDU fundraising event in 1994.

The following day, he said, Mr Schreiber had appeared at his office and handed him a party donation of 100,000 deutschmarks in cash - whether in a suitcase or a bag, he couldn't remember. The CDU leader said he had wondered if the man wanted a receipt, but he apparently didn't, so Mr Schaeuble instead sent him a thank-you note and a signed and dedicated copy of his latest book.

At a packed press conference in Berlin the next day, Mr Schauble had a lot of explaining to do, though he denied he had done anything wrong and said he saw no reason to resign. The money, he admitted, had not been declared until well over a year later. But that, he said, had been the fault of the then party Treasurer, Brigitte Baumeister. Unused to handling such large sums of cash, she had simply popped it into the office safe. Eventually, it was declared - not as a donation, but as 'other income'.

Several hurdles

Frau Baumeister was not around to give her own version of events, and has proved remarkably difficult for the German press to locate. But Mr Schaeuble may find that his version of events proves unsatisfactory for both his party and the public.

Already, there have been calls for his resignation from some leading CDU members, despite an attempt to close ranks. Yet there are several hurdles for any new would-be CDU leader.

During the era of Helmut Kohl, the CDU was a one-man party with Mr Kohl its undisputed leader for 25 years, until 1998. Anyone who defied him during that period found their career grinding to a rapid halt.

So, an entire generation of western German CDU politicians who made it to the top did so under the patronage of Mr Kohl. Now they are automatically suspect in this affair, whether or not they knew of the secret party funds.

The public suspects that Wolfgang Schaeuble may simply be the first in a long line of CDU politicians who find their memories of financial dealings in the 1990s suddenly and remarkably refreshed by the investigation and a parliamentary committee of inquiry.

All this misfortune, one might think, would bring howls of glee from the governing Social Democrats and Greens. But if they are gloating at all, they are doing so very quietly indeed.

Revelation

The CDU scandal has conveniently taken the attention away from the SPD's own difficulties over questionable free flights provided by a state bank for some of its leading politicians, while the Greens may have inadvertently but nonetheless illegally diverted MPs' office allowances into central party funds.

These are fascinating days in German politics - but they have left the German public wondering which politician, if any, they can trust after the revelation that Helmut Kohl, the man who dominated the European stage for so long, appears to have been less than true to the spirit of the law.

The final word goes to a reader of Germany's biggest-selling tabloid, the Bild. He has offered a cash reward of 1,000 deutschmarks to the first politician who proves their honesty - though he does not say if the reward would come in a suitcase or a bag, or if it had to be declared.