BERLIN (AP) — Divisions between German Chancellor Angela Merkel and her coalition partners appear to be widening over plans for an ambitious law to curb greenhouse gas emissions.

Environment Minister Svenja Schulze of the center-left Social Democrats said Monday it would be “very sensible” for Germany to join other European countries in setting a target of ‘net zero’ emissions by mid-century.

The idea proposed by France and eight other countries didn’t receive backing from Merkel at last week’s European Union summit.

Speaking ahead of a climate change meeting of 35 countries in Berlin, Schulze also insisted that Cabinet should agree on a “strong” climate law this year that includes some form of carbon tax.

The leader of Merkel’s center-right party, Annegret Kramp-Karrenbauer, has instead favored expanding an EU-wide carbon trading system.