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.

“Social Democracy is back!” Ms Ypsilanti shouted to her cheering party workers.

The result: turbulent times ahead for German politics as the grand coalition parties, the Christian Democrats and the Social Democrats, begin divorce proceedings before the 2009 general elections. The gloves are now off, said Jürgen Falter, a leading political scientist from the University of Mainz. “The tensions in the grand coalition in Berlin will now increase – the Government will be strained to the very limit,” he said. “Plainly the Government in Berlin will not be able to undertake any major reform initiative.”

Mr Koch used to be an internal party rival to Mrs Merkel, a conservative who was always suspicious of watering down policy by allying with the Social Democrats. When and if he is formally declared the loser of the election, the best he can hope for, party insiders say, is a Cabinet position under Mrs Merkel, probably as Economics Minister, after a predicted reshuffle. In German politics the move from regional prime minister to federal Cabinet minister is a big demotion. In theory that should please Mrs Merkel – one more potential thorn removed from her side – but, instead, there were nothing but worried faces in party headquarters last night.

Angela Merkel, the German Chancellor, was last night dealt a political body blow as one of her key allies struggled to stay in power after a bitterly contested regional election.

Her Christian Democratic party was thunderstruck when voters in Hesse abandoned the state’s prime minister, Roland Koch, an outspoken conservative who was once tipped to be a future chancellor. Mr Koch admitted the scale of his defeat — “this is not personally easy for me” — but said he would continue to fight for his position until the last vote was counted.

Provisional results seemed to show that Mr Koch had been confirmed in the premiership by a wafer-thin margin: 36.8 per cent for the Christian Democrats, 36.7 per cent for the rival Social Democrats led by Andreas Ypsilanti. Social Democrats were last night considering a call for a recount. In Germany the strongest party has the right to form a governing coalition — but in Mr Koch’s case the ruling line-up would have little legitimacy and be very fickle indeed. If the result is confirmed he will attempt to form a government with the liberal Free Democrats who won 9.3 per cent of the vote.

In the end though Mr Koch — in or out of his job — was washed up as a leading political force in Germany. His campaign of mobilising voters by stirring anger about street crime committed by young immigrants failed and he can no longer be counted as Mrs Merkel’s crown prince.

The Social Democrats are convinced their time has come, that there is a future outside the increasingly chafing harness of its national partnership with Mrs Merkel. “Social Democracy is back!” Ms Ypsilanti shouted to her cheering party workers.

The result: turbulent times as the grand coalition parties begin divorce proceedings before next year’s general election. The gloves are now off, said Jürgen Falter, a leading political scientist from the University of Mainz. “The tensions in the grand coalition in Berlin will increase — the Government will be strained to the very limit.” It is now unlikely that the Government in Berlin will be able to undertake any important reforms.

“Germany is shifting to the left quicker than anyone realised,” said a senior Christian Democrat adviser, “and we don’t yet have an answer.” The Left party, which includes former communists from East Germany, entered both the Hesse and Lower Saxony parliaments yesterday — their first foothold in western Germany.

In Lower Saxony regional voting, Christian Wulff, the prime minister, was confirmed in office. He will rule with the Free Democrats. He now ranks as Mrs Merkel’s crown prince.

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