Germany: The German constitution says a new Bundestag must be in place by October 18th, a month after the general election, where a majority of the deputies (the so-called chancellor majority) must approve the chancellor candidate.
If this vote fails, any number of further votes can be held in the next 14 days, with candidates from all parties trying to reach the chancellor majority.
If this fails, a third voting phase begins where the winner is the candidate with the most votes (a simple majority).
The president then has seven days to nominate this candidate as chancellor or call for fresh elections.
If the SPD nominated Mr Schröder, he could theoretically receive the backing of the Left Party but ask the president for fresh elections rather than have his government beholden to the Left Party lead candidate.