The surprise decision by Social Democratic leader Sigmar Gabriel to surrender the SPD’s candidacy to a more popular figure, former European Parliament President Martin Schulz, reinvigorates the fortunes of a party that has become the perennial also-ran to Merkel’s Christian Democrats during her tenure. “Schulz is someone who will compete with a more aggressive stance during the election campaign,” said Henrik Enderlein, professor of political economy at the Hertie School of Governance in Berlin, in an interview Tuesday.