would emerge or not.
His party colleague Alexander Dobrindt, known for his acerbic snipes at the Greens, declared darkly that the talks "are hanging by a thread".
Looming over the political drama is the prickly issue of immigration, a hot-button topic since Merkel in 2015 threw open German borders to a mass influx of over one million asylum seekers.
While the CSU has been sharply critical and wants to cap future arrivals at 200,000 a year, the Greens argue that more refugees should be allowed to bring their families.
Deep differences also remain on climate policy, where the Greens want to phase out dirty coal and combustion-engine cars, while the conservatives and FDP stress the need to protect industry and jobs.
The Greens face a party congress in a week’s time, where their rank-and-file members will give the thumbs up or down on the concessions their leaders may have wrested from the other parties.
Martin Schulz of the centre-left Social Democrats (SPD) -- Merkel’s former junior coalition partner that went into opposition after a stinging election loss -- reemerged to criticise the painful process.
He charged that the four parties were searching for the "lowest common denominator" in an atmosphere of "maximum mutual distrust", led by Merkel, whom he labelled the "world champion in vagueness".
Schulz also charged that the odd alliance would diminish Germany’s role in the EU and contribute to the "paralysis of Europe".
The Frankfurter Allgemeine Zeitung daily commented that, despite the hurdles, "Merkel can’t afford to fail, because the SPD... won’t come to her rescue again".
The smaller parties, it said, "are already fighting at the expense of the chancellor, who won’t necessarily get the credit if the talks succeed, but who will certainly be blamed if this experiment fails".
Fresh elections would heap pressure on all parties, the broadsheet added, but especially on the chancellor "because then Merkel’s star will fade even more quickly, maybe even for good."