BERLIN — The potential partners in Germany’s next government stressed Thursday their joint wish to form a pro-European administration that nurtures strong ties with France, though gave few details as they struggled to bridge differences on other tricky policy issues.

Last month’s election left Chancellor Angela Merkel trying to form an untried coalition that brings together her conservative Union bloc, the pro-business Free Democrats and the traditionally left-leaning Greens.

Exploratory talks started last week. On Thursday, negotiators began tackling the thorny topics that divide them — including immigration, with conservatives pushing hard to limit the number of migrants the country accepts.

They ended several hours of talks without finding common ground on immigration and climate protection, a key issue for the Greens. Negotiators hope to try again next week.

Peter Tauber, the general secretary of Merkel’s Christian Democratic Union, said the parties still need to hold more discussions on issues such as the European Union’s relationship with Turkey. The conservatives have long argued that Turkey ultimately shouldn’t join the EU.

Nonetheless, “it is very clear for all of us that we want a strong, united Europe, and that as the basis of that we see close cooperation with France,” Tauber told reporters during a break in the talks. “But of course what matters is with what aims, with what issues that can be achieved.”

His counterpart from the Free Democrats, Nicola Beer, underlined the desire to bolster the EU and relations with France. However, her party has long talked tough on aid to struggling eurozone countries, and Beer stressed its insistence that “there should be no automatic (financial) transfers.”

French President Emmanuel Macron recently laid out his vision for a more unified Europe, with a joint budget for countries sharing the euro currency, an idea viewed with some suspicion in Germany.