Head of the Social Democratic Party SPOe Christian Kern delivers a media statement in Vienna, Austria, September 18, 2018. REUTERS/Lisi Niesner

VIENNA (Reuters) - Opposition leader Christian Kern said on Tuesday he would run as top candidate for the Austrian Social Democrats in the European Parliament elections next year, aiming to help build a strong counterweight to growing nationalist forces.

The 52-year-old former chancellor, whose party lost power last year, is known for his strongly pro-European stance.

“We see that the concept of a liberal, open-minded democracy is greatly challenged by the Orbans, the Kaczynskis, the Straches and the Salvinis,” he told reporters in Vienna.

He was referring to a string of nationalist politicians - Hungary’s Prime Minister Viktor Orban, the leader of Poland’s ruling Law and Justice (PiS) party, Jaroslaw Kaczynski, Austria’s far-right Vice Chancellor Heinz-Christian Strache and Italy’s Deputy Prime Minister Matteo Salvini.

“It is the most important challenge for us Social Democrats to ensure that Europe’s heritage is preserved,” Kern said in his short statement.

Kern’s move to Brussels could help the image of the Austrian Social Democrats, who have been too preoccupied with internal struggles since the election to provide strong opposition to the conservative-far right coalition led by Sebastian Kurz.

Kern said he would resign as national party leader in May at the latest to fully focus on his new task. It is not yet clear who will replace him.