Wolfgang Schaeuble inherited the leadership of the CDU from former Chancellor Helmut Kohl following the party's election defeat in 1998.

He served as Interior Minister in the Kohl government and was chief whip of the CDU, building a reputation as a cross-party deal-maker in Germany's complex system of federal government.

He also came to be regarded as the chancellor's political confidante and in return for his loyalty was the only candidate allowed to rise to a position of influence within the party. When Mr Kohl finally stepped down, Mr Schaeuble, the chancellor's loyal lieutenant, was his natural successor.

A wheelchair user following an assassination attempt eight years earlier he has fought hard to steer his party through the storm brought about by the growing finance scandal.

When the allegations first emerged last year he promised there would be a party-wide investigation but he acted carefully to minimise political damage to his predecessor and one-time mentor.

However by the beginning of this year it was clear that the CDU's party funding scandal would to engulf him as well.

TV admission

His reputation took a particular hammering when he admitted during a TV interview that he had met the arms dealer at the centre of the scandal, Karlheinz Schreiber, at a CDU fundraising event in 1994 and accepted an undeclared DM100,000 cash donation from him.

However he denied media reports that he had doctored party records three years later to cover his back, and insists that he did nothing wrong.

Nonetheless just days after the interview, Mr Schaeuble, once one of the most respected politicians in Germany, was heckled and jeered by CDU supporters at a campaign rally, some of whom shouted that he should resign.

Political commentators and some party members had urged the CDU leader to stand down, saying his admission meant his position had become untenable.

But until recently Mr Schaeuble had stated publicly that there was no question of him quitting.

"I will do everything in my power to lead the CDU out of this difficult situation," he told Germany's Welt am Sonntag newspaper in January.

"This great party of the centre is too important for the stability and the future of this republic to let it suffer lasting damage from this affair."