Germany's center-left Social Democrats won the biggest share of the vote in a national election Sunday, narrowly beating outgoing Chancellor Angela Merkel 's center-right Union bloc in a closely fought race that will determine who succeeds the long-time leader at the helm of Europe's biggest economy.

The Social Democrats' candidate Olaf Scholz, the outgoing vice chancellor and finance minister who pulled his party out of a years-long slump, said the outcome was “a very clear mandate to ensure now that we put together a good, pragmatic Government for Germany.”

Despite getting its worst-ever result in a federal contest, the Union bloc said it too would reach out to smaller parties to discuss forming a government, while Merkel stays on in a caretaker role until a successor is sworn in.

Election officials said early Monday that a count of all 299 constituencies showed the Social Democrats received 25.9% of the vote, ahead of 24.1% for the Union bloc. No winning party in a German national election had previously taken less than 31% of the vote.

Armin Laschet, the governor of North Rhine-Westphalia state who outmaneuvered a more popular rival to secure the nomination of Merkel's Union bloc, had struggled to motivate the party's base and suffered a series of missteps.

“Of course, this is a loss of votes that isn't pretty,” Laschet said of results that looked set to undercut by some measure the Union's previous worst showing of 31% in 1949. But he added that with Merkel departing after 16 years in power, “no one had an incumbent bonus in this election.”

Laschet told supporters that “we will do everything we can to form a government under the Union's leadership, because Germany now needs a coalition for the future that modernizes our country.”