Merkel's Christian Democrats have already lost control of two states to the Social Democrats this year  [GALLO/GETTY]

Angela Merkel's centre-right coalition could suffer another blow at the polls in a regional election in Germany's poorest state, Mecklenburg-Vorpommern.

The German chancellor's Christian Democrats (CDU) have been junior coalition partners to the centre-left Social Democrats (SPD) in the sparsely populated state on the Baltic shore.

However, Sunday's key regional vote could see the CDU knocked out and replaced by the Left party or even by Germany's resurgent Green Party.

The CDU has slumped in national polls and already been punished in five regional elections this year, losing control of two states to the SPD this year, in part due to general discontent over Merkel and her hesitant leadership during the eurozone debt crisis.

Merkel's coalition partners, the Free Democrats, are also struggling and could lose all their seats in Mecklenburg-Vorpommern's state assembly.

Opinion polls in Mecklenburg-Vorpommern put the SPD at about 37 per cent, well above their 30.2 per cent in 2006 with the CDU polling about 27 per cent, down from 28.8 in 2006. The Left are on 17 per cent after 16.8 per cent five years ago.

Greens riding high

The Greens, riding high in national polls in the wake of the Japanese nuclear disaster, are expected to win nine per cent after 3.4 per cent in 2006.

If the Greens clear the five per cent hurdle in the state for the first time, the environmental party will have seats in all 16 states for the first time.

A poor result for the CDU and being ejected from the government in Mecklenburg-Vorpommern would be a personal setback for Merkel two years ahead of federal elections.

The chancellor, whose parliamentary constituency is in the region, campaigned heavily there with nine public appearances.

The region, home to 1.6 million, has long been one of Germany's most economically depressed with unemployment levels at 12 per cent, more than triple the jobless rate in more prosperous southern Germany.

Wages in Mecklenburg-Vorpommern are the lowest in Germany and even below European Union averages, while the population has shrunk since reunification as the region's East German-era industries collapsed.

Those economic conditions have helped the far-right NPD, which could win seats in the assembly again after winning 7.3 per cent in 2006.

Another election defeat for the CDU could cause further nervousness among backbenchers in the Berlin parliament worried about their job security.

Merkel's coalition faces a difficult vote on the eurozone bailout on September 29 and there are already
fears that not enough coalition deputies will back Merkel.

Source: Agencies