Angela Merkel faces a rocky political road ahead as she battles to hang on until 2021 as German chancellor, after her junior coalition partner SPD elected a left-leaning leadership duo. Rank and file Social Democrats late Saturday delivered a humiliating blow to Finance Minister Olaf Scholz’s run for co-chair of his centre-left party, picking instead two relative unknowns as their new leaders. The shock result heralded a week of uncertainty for the coalition, with next Friday a key date as the SPD is to vote on whether to stay in government when it meets for its annual congress.