Angela Merkel, the German Chancellor, was last night dealt a political body-blow after one of her key allies appeared to lose a bitterly contested regional election.

Her Christian Democratic party was thunderstruck when voters in the state of Hess abandoned the region's prime minister, Roland Koch, an outspoken conservative who was once tipped to be a future Chancellor of Germany. Mr Koch admitted the scale of his defeat - "This is not personally easy for me" - but said that he would continue to fight for his position until the last vote was counted.

As exit polls firmed up into concrete results it appeared that Mr Koch's party had not only lost its absolute majority but was also no longer the biggest party in the region. However, the margin of defeat was small: the Social Democrats, led by 50-year-old Andrea Ypsilanti, were on 37.2 per cent, the Christian Democrats on 36.6 per cent. It could be that the clinching element would be a handful of postal votes, an analyst from state televion said.

In the end, though, what mattered was that Mr Koch - in or out of his job as prime minister - was now washed up as an influential political force in Germany and could no longer be counted as Ms Merkel's crown prince.