Chancellor and Economy and Energy Minister Sigmar Gabriel and German Chancellor Angela Merkel | Adam Berry/Getty Images SPD chief: Angela Merkel ‘doesn’t have answers for Germany’s future’ Sigmar Gabriel said Merkel is only running for fourth term because conservatives would be lost without her.

The leader of Germany's Social Democratic party (SPD) Sigmar Gabriel lashed out at Chancellor Angela Merkel and vowed that his party will try to avoid a grand coalition with her Christian Democratic Union (CDU) following next year's elections.

Merkel announced last month that she will run for a fourth term in office in the general vote that is scheduled to take place sometime in autumn 2017.

Gabriel, who is also serving as Germany's economy minister and deputy chancellor, said Merkel is not up to taking on the challenges facing the country and said she's seeking another mandate because her party “would be completely leaderless” without her.

“She does it out of a sense of duty,” he said in an interview with the Rheinische Post that was published on Saturday. “But she doesn't have any answers for Germany's future.”

Merkel's CDU failed to bridge the widening gap between the "wealthy and the poor, the well-off and the abandoned, the satisfied and the furious,” Gabriel said.

“It is clear to us that we want to avoid a grand coalition,” Gabriel said, adding that the SPD is willing to partner with other political parties. “In the end, we will form a coalition with those who will enable us to implement as many of [our goals] as possible.”

While openly challenging Merkel, Gabriel evaded the answer to the question if he will run against her as the SPD's candidate. "We've decided a long time ago that we would nominate our candidate for the chancellor in January,” he said.