Schroeder kicks off poll campaign

And in an echo of his 2002 campaign style, he warned the US against the threat of military action against Iran.

Mr Schroeder's opposition to the Iraq war was seen as a key swing factor in the last election campaign.

He has until 18 September to claw back a 13-point lead held by the Christian Democrats over his Social Democrats.

Christian Democrat leader Angela Merkel will become Germany's first female leader if she wins.

"We are in a similar situation to 2002 - the other side thought that time too that they had already won, but it turned out differently"
Gerhard Schroeder

Mr Schroeder formally launched the campaign at an outdoor rally in his home town of Hanover, seizing on the Iran issue a day after US President George W Bush said all options were "on the table".

"Let's take the military option off the table. We have seen it doesn't work," Mr Schroeder told the rally to rapturous applause.

Mr Schroeder remains a more popular figure than Ms Merkel among voters, despite her party's higher showing in the polls. Her standing may have suffered further damage by political infighting among conservatives, which Mr Schroeder has sought to capitalise on.

An opinion poll released on Saturday suggested the Christian Democrats were 13 points clear on 41% - two points down - while the Social Democrats had inched their way back by two points to 28%.

Mr Schroeder engineered the early elections amid faltering public support for a controversial reform programme.

He decided to risk defeat in pursuit of the prize of a fresh mandate for the reforms, which are trying to slim down the welfare state and boost economic performance.

Germany's Supreme Court has still to confirm that the elections can go ahead on 18 September, after critics claimed the parliamentary manoeuvring which brought about the early poll broke the rules of the constitution.

BBC Berlin correspondent Ray Furlong says the chancellor has appeared more relaxed as the Social Democrats close the gap on the Christian Democrats, bursting with jokes, smiles and confidence.

Mr Schroeder believes he has wind in his sails, he adds.

In Germany's last general election in 2002, Mr Schroeder came from behind to snatch victory from then-conservative challenger Edmund Stoiber, after severe floods and the anti-Iraq war feeling helped him attract last-minute support.

"We are in a similar situation to 2002. The other side thought that time too that they had already won, but it turned out differently," Mr Schroeder told the Westfaelische Rundschau newspaper.

A new left-wing party is causing some worries for the Social Democrats. Headed by their own former leader Oskar Lafontaine, the Left Party brings together former communists from eastern Germany and disaffected Social Democrats in the west.

A handful of minor parties have also registered their intention to stand.

The Anarchist Pogo Party of Germany, the Party of Bible-faithful Christians and the Grey Party (for senior citizens) will take their place alongside the more traditional contenders on ballot papers.

The Anarchist Pogo Party will be campaigning under slogans including: "You work - we'll enjoy ourselves".