Germany's centre-left Social Democrats (SPD) have claimed victory in the federal election, telling the party of outgoing Chancellor Angela Merkel it should no longer be in power.
SPD leader Olaf Scholz said he had a clear mandate to form a government, while his conservative rival Armin Laschet remains determined to fight on.
The two parties have governed together for years.
But Mr Scholz says it is time for a new coalition with the Greens and liberals.
Preliminary results gave his party a narrow election win over the conservatives who suffered their worst-ever performance.
The Greens and pro-business FDP attracted the most support from the under-30s, in an election dominated by climate change and by differing proposals on how to tackle it. The Greens made history with almost 15% of the vote, even though it was well short of their ambitions.
It was the tightest race in years, bringing an end to the post-war domination of the two big parties - Mr Scholz's SPD and his rival's conservative Christian Democratic Union (CDU).
Merkel stays in place for now
Exit polls predicted a dead heat, but this election was unpredictable from the start, and the result was never going to be the end of the story. For one thing, the outgoing chancellor is going nowhere until the coalition is formed - and that may have to wait until Christmas.
The main parties want a new government in place by the time Germany takes over the leadership of the G7 group of nations in January.
The next chancellor's task is to lead Europe's foremost economy over the next four years, with climate change at the top of voters' agenda.
Mr Scholz's SPD supporters greeted him in raptures, but it was only later when his party edged into the lead that he told a televised audience the voters had given him the job of forming a "good, pragmatic government for Germany".
Speaking on Monday he said there were three parties that were on the up - his party, the Greens and the liberals - and it was time for the conservatives to back down. "I think that the people in Germany want the Christian Democratic Union in opposition. This is their result now, what they decided during the election," he said in English.
