Germany's oppositional Social Democratic Party (SPD) hopes to win back power by moving left of center. If Chancellor Angela Merkel fails to form a coalition after the 2013 elections, one of the three men in the photo is expected to take her place.

That's the message from the three-day day SPD party conference that ended Tuesday in Berlin. The three are (from left) party chairman Sigmar Gabriel, former finance minister Peer Steinbrück, and former foreign minister Frank-Walter Steinmeier.

"We want to govern," Gabriel told the delegates. The Social Democrats were aiming to come across as decisive and reliable. 

Together with the Greens, the Social Democrats want to bring about the end of the current center-right ruling coalition in parliamentary elections in fall 2013.

In a lively and engaging speech, Gabriel, who was reelected as party chairman with a big majority on Monday, said the party wanted to restore hope and social justice to Germany.

A stronger leader

Gabriel has held the post of party chairman since 2009, when he was voted in at a party conference in Dresden after a catastrophic performance in national elections.

The oldest party in Germany, known as "Aunty SPD," polled just 23 percent of the vote, their worst-ever result on a national level. Gabriel found himself with the Herculean task of winning back voters lost to the left, without offending the middle ground.

Above all he had to speak to those who had turned away from the SPD following reforms to the labor market under the government of Gerhard Schröder in the 1990s.

Two years on, the party has recovered somewhat under Gabriel's leadership. Polls show around 30 percent support among voters. That's still far below their heyday as a real people's party.

But the trend is heading upward, and the SPD was keen to appear self-confident, upbeat and above all united at this year's party conference.

They even managed to defuse an argument about tax policy. The party's left had demand a 53 percent "rich tax" for those who earn above 125,000 euros a year.

The party leadership had said it was against such plans and proposed more moderate tax rises. The compromise suggestion, which won the day, demanded a rise in the top rate of tax from 42 to 49 percent. The compensation tax on interest earnings would also rise from 25 to 32 percent.

Three candidates for chancellor

But despite attempts to present a harmonious front, unrest is growing in the party ranks. It's still unclear who should lead the party when the national election campaign gets underway in roughly 18 months' time.

At the moment there are three candidates in the race. Alongside Gabriel, there are Steinbrück and Steinmeier. Both Steinbrück and Steinmeier made crucial contributions to the conference, and both made much-anticipated speeches.

It was above all Steinbrück's speech, scheduled for the last day of the conference, which was eagerly anticipated by the 500 delegates and numerous journalists.

But his comments on finance and tax policy were met with only polite applause. The former finance minister, who is on the more conservative and economically liberal wing of the SPD, may not hold any office, but he consistently scores well in opinion polls, and his candidacy is supported by former Chancellor Helmut Schmidt.

The grandfather man of social democracy
Schmidt, - the "very old man," as he describes himself - is seen in Germany as an elder statesman par excellence.