Germany's main centre-left party will negotiate with Angela Merkel over a possible "grand coalition" spanning left and right.
The Chancellor needs to attract a new junior partner after falling short of a parliamentary majority in last week's elections and seeing her party's parter drop out of parliament entirely.
Her centre-right Christian Democratic Union (CDU) and its Bavarian sister party the Christian Social Union, jointly toasted its best result since reunification in the poll, with 41.5 per cent of votes. This left the party on 311 Bundestag seats - tantalisingly close to the 316 required for a majority.
And yesterday the chairman of the centre-left Social Democratic Party (SPD) - which took 192 seats - announced preliminary coalition talks with Ms Merkel.
At the end of a four-hour meeting, Sigmar Gabriel said: "The SPD decided that we'll be available for exploratory talks with Frau Merkel.
"But the party did not open the door for full-scale talks. If Frau Merkel invites us to exploratory talks we'll take the findings from that meeting back to the party leaders before deciding if we're open for full negotiations."
He said that any formal decision on coalition would be put to the party's 472,000-strong membership, ahead of its mid-November conference.
Such a coalition - like the one which Merkel helmed from 2005 to 2009 - would be popular with voters. A Politbarometer opinion poll on ZDF television reported that 58 per cent would support it.
As well as giving Merkel a huge majority of 503 seats, it could ease the passage of legislation, given the centre-left control of the country's upper chamber, the Bundesrat.
But Mr Gabriel is aware of the pitfalls such a move could present. His party scored its lowest post-war vote share after after the 2005-09 partnership, and hasn't fully recovered electorally. And the pro-business Free Democrats, Merkel's most recent partners, suffered a staggering fall from a 14.6 per cent vote share in 2009 to 4.8 per cent last week.
Mr Gabriel said: "The SPD is not queuing to be next after Mrs Merkel ruined her previous coalition partner."
There are other party combinations which would leave a majority. The Green Party, which now holds 63 seats, could also be an option for Merkel, but this would be less popular with the CDU membership.
Between them, the SPD, the Greens and the radical Left Party could command a slender majority of 319. But such an option hasn't got much consideration, because the Left - successors to the East German Communist Party - are seen as unreliable on policy.
In the absence of a coherent coalition, President Joachim Gauck could dissolve the Bundestag and call fresh elections.