The candidate named by Germany's Social Democrats to challenge Chancellor Angela Merkel, Martin Schulz, has vowed to fight populism if his party wins the elections due in September.
While the centre-left SPD is slightly behind Merkel's conservatives in the latest Emnid poll, it showed Schulz should be able to take power with a left-leaning alliance involving the far-left Linke and Greens in what would be the first time Germany has ever had a "red-red-green" coalition at the national level.
The latest polls put the party nearly neck and neck with the ruling Christian Democrats, who had until recently enjoyed a double digit lead.
"We're back!" Schulz told around 600 delegates at a party meeting in Berlin shortly before he was chosen as SPD leader in a vote in which all 605 of the valid votes gave him a "yes".
The tally in Sunday's vote will be a measure of Schulz's support.
He replaces Sigmar Gabriel, who stepped down as chairman in January in an attempt to improve the party's chances. Merkel's has 33% support, with the SPD on 32%.
Schulz, who apart from serving as a provincial mayor for several years has not held a high-profile political post in Germany but instead has made his career in European politics, called the result the "prelude to conquest of the chancellery". You have in the SPD the most decisive enemy that is possible in this country, " Schulz declared. In a nod to critics on the left, Schulz is proposing to expand benefits for jobless who agree to retraining.
The SPD, or Sozialdemokratische Partei Deutschlands, is now a major partner of the ruling coalition and had been trailing Chancellor Merkel's Christian Democratic Union (CDU) in opinion polls for years before Schulz's nomination as party candidate for chancellery. The March 6-10 survey of 2,505 people has a margin of error of plus or minus 2.5 percentage points.