The leader of Germany's Social Democrats (SPD) and the centre-left party's putative chancellor candidate broke with German political custom on Saturday and said he hoped the United States elects Barack Obama in November.

SPD chairman Kurt Beck said the whole world would be better off with a President Obama instead of another Republican administration. By endorsing the Democrats, Beck broke a tacit rule to refrain from any intervention in foreign elections.

"I'd like to say very openly that I really do hope that he wins," Beck told journalists after a speech in the eastern town of Erfurt.