Germany's Social Democratic Party has chosen the Foreign Minister as their candidate for chancellor in next year's election.
Frank-Walter Steinmeier will stand against Angela Merkel of the Christian Democrats.
The two parties share power in a coalition government.
Mr Steinmeier says the current financial crisis is proof that the reign of radical market ideology had ended with a bang, and a new era had begun.
"This new time that is dawning now has to become our time, the time of social democracy," he said.
"We are experiencing a time of decisions now, now it depends on us. In one year, I want to be working as chancellor so that we can steer our country in the right direction."
Mr Steinmeier accused Mrs Merkel's party of trying to appear more socially democratic since the financial crash, although in the past, he said, it had opposed stricter regulation of the markets.