Delegates to the congress of Germany's Social Democrats voted overwhelmingly here Thursday to keep Martin Schulz as party leader hours after approving a motion to enter talks with conservative Chancellor Angela Merkel on forming a government.

Schulz prevailed by a vote of 508-97 with 15 abstentions.

He was first elected leader in March by a margin of 605-0 with three abstentions.

"To all those who have lost confidence in me since March, I tell you that I will do everything possible to regain your confidence," Schulz said during the first day of the party congress in Berlin.

Schulz's re-election came at the end of an intense session dominated by debate over whether the Social Democratic Party (SPD) should entertain the idea of renewing the grand coalition with Merkel's Christian Democrats (CDU).

Both of Germany's traditional major parties fared poorly in the Sept. 24 parliamentary elections that marked the end of four years of CDU-SPD government.

While the SPD had vowed not to be part of another CDU-led government, some in the party signaled a softening of that position following the collapse of Merkel's bid to form a coalition with the Free Democrats and the Greens.

The motion to open talks with the CDU was approved by a show of hands amid fierce opposition from some party factions, notably the Young Social Democrats, known as Jusos.

In a nod to the concerns of the Jusos and other critics, the terms of the motion require the party leadership to convene another congress to approve or reject any plan for reviving the coalition with the CDU.

Schulz said that talks with Merkel could lead to agreement on a "new form" distinct from formal coalition.

"Perhaps cooperation, perhaps tolerance, perhaps a coalition. Give us the opportunity to explore all options," the former speaker of the European Parliament said.

The Jusos contend that joining another Merkel-led administration would only make it more difficult for the SPD to engage in a much-needed overhaul.

"A new grand coalition cannot be a result of these conversations. Conversations, yes. Grand coalition as it has been up to now, no," Jusos leader Kevin Kühnert said.