The weekend putsch that restored reformers to the helm of the Social Democratic party has sent an electric charge through German politics. Now that the SPD has nailed its colours to the mast, there is at the same time a risk of paralysis within the grand coalition led by Angela Merkel, the Christian Democrat chancellor, as the two parties seek to govern and compete in the year until the next general election.

Whether the two governing parties opt for competitive populism or scramble for the political centre – or some combination of both – the next 12 months will be very tricky.