Germany's Greens played down prospects of forming a government with Angela Merkel's conservatives, a day after a first round of exploratory coalition talks highlighted policy differences between the parties on clean energy and industry.
Despite agreeing to meet again with her next week, Greens politicians made clear on Friday that they had found little common ground with Merkel, whose Christian Democrats (CDU) are also holding talks with the center-left Social Democrats (SPD).
"Frankly this is something we didn't want and the CDU didn't want. But we have to work out how to ensure a stable, sustainable government for the next four years," said Greens parliamentary leader Katrin Goering-Eckardt.
"And after yesterday evening, I can't imagine how we could do that for four years," she added. The Greens have shared power with the CDU at state level, but never nationally.
The SPD, by contrast, served under Merkel in a 'grand coalition' from 2005 to 2009. They are widely seen as the more likely partner for the CDU and its Bavarian sister party, the Christian Social Union (CSU).
Merkel will hold a second round of exploratory talks with the SPD on Monday, a day before she meets again with the Greens. Formal coalition talks could start in the second half of October and are expected to last up to two months.
CDU second-in-command Hermann Groehe told German TV that his party had "more in common" with the SPD on issues like industry policy, especially since the Greens had veered further to the left in the election campaign.
He denied that Merkel was pursuing talks with the Greens simply to gain a stronger negotiating position with the SPD, which is reluctant to partner with her again after shedding supporters during the 2005-2009 coalition.
The SPD has said it will give 472,000 card-carrying members the last say in any decision to form another coalition with Merkel, adding an element of risk to the process.
Some conservatives see a historic opportunity in linking up with the Greens, who have grown from a 1970s hippie group to the world's most successful environmentalist party, gaining executive experience in power with the SPD in 1998-2005.
But Goering-Eckardt said that while her party supported Merkel's decision to accelerate Germany's exit from nuclear power, it opposed energy subsidies for industry and her attempts to delay new European Union caps on vehicles' carbon emissions.
Merkel disagrees with the SPD and Greens' demands for a blanket minimum wage and higher taxes on the rich to fund more spending on infrastructure, education and research.
There are also differences on how to tackle the euro zone debt crisis, though both of the center-left parties supported her government in votes on the bailouts.
"We have to hold serious exploratory talks but I must say people are very, very skeptical, because we differ not on one issue but many," said Greens co-chairman Cem Oezdemir.
Germany's European partners worry that drawn-out coalition talks could delay decisions on measures to fight the euro zone crisis such as an ambitious plan for a banking union.
(Additional reporting by Christian Goetz; Editing by Noah Barkin)