Chancellor Olaf Scholz’s ruling coalition suffered an embarrassing blow over key climate legislation after Germany’s top court stopped lawmakers from voting this week on a controversial ban on fossil fuel home-heating systems.

In a highly unusual intervention in the legislative process, the Federal Constitutional Court ruled that lawmakers in the lower house of parliament hadn’t had enough time to assess the complex legislation. The decision delays the passage of the contentious law, which exposed fractures in Scholz’s three-party alliance and contributed to declining approval ratings in the polls.

Scholz’s Social Democrats, the environmentalist Greens and the pro-business Free Democrats had hoped to ram the bill through the lower house in its final session before the summer break to put an end to months of in-fighting and provide households and companies with a measure of clarity.

The court though granted a petition from a member of the main opposition Christian Democrats to postpone Friday’s planned vote. The parliamentarian succesfully argued that his rights as a legislator were being infringed by the fast-track process.

Although the legislation is still likely to come into force next year as planned, it’s a particular setback for Economy Minister Robert Habeck, the Greens’ vice chancellor who was its main architect. He’s been the target of blistering attacks for months over the plan, which the Bild tabloid labeled “Habeck’s heating hammer.”

Read More: German Greens Are in Crisis Like the Rest of Scholz’s Coalition

“This shows that climate protection can’t be achieved with a crowbar, but only through effective and thorough deliberation in the German Bundestag,” Friedrich Merz, head of the CDU, said in a statement. “Olaf Scholz and his government would be well advised to use the ruling to pause for thought.”

The public outcry over the heating law has been cited as one reason for the recent rise in support for the far-right Alternative for Germany. The anti-immigrant party, which is particularly strong in the former communist eastern regions, questions whether global warming is caused by humans and has been an energetic opponent of the legislation.

In several polls published in recent weeks, the AfD has leapfrogged Scholz’s SPD into second place behind the CDU/CSU bloc, with the Greens in fourth.

Senior officials from the three ruling parties will meet on Thursday morning to discuss the next steps, including possibly holding an extra parliamentary session during the summer break. Otherwise, the vote will be held when parliament goes back to work in September.

“A special session of the Bundestag is one option and the court itself also mentioned this,” Britta Hasselmann, a co-leader of the Greens’ parliamentary group, said Thursday in an interview with Deutschlandfunk radio.

Advocates of the bill, which would essentially ban all new fossil-fuel boilers, say it’s crucial for Germany to meet its goal of slashing carbon emissions by two-thirds by 2030 from 1990 levels. Critics of the measure contend it goes too far and would impose excessive costs on low-income families.

Germany’s courts have intervened in climate policy in the past. In 2021, the constitutional court in Karlsruhe forced Angela Merkel’s administration to revise its climate targets, ruling that the government was putting future generations at risk by delaying the bulk of planned cuts in greenhouse-gas emissions to after 2030.

Read More: Merkel’s Conservatives Suffer Climate Setback After Court Rebuke

Scholz’s coalition parties reached a deal on the bill last month, after watering down some of the provisions. A draft, however, didn’t reach members of parliament in time to give them at least 14 days to consider it before a vote is required, according to CDU lawmaker Thomas Heilmann, who filed the complaint.

The legislation has been a particular source of tension between the Greens and the FDP. Habeck accused his coalition partners of going back on their word after earlier delays in sending the law to parliament, while the FDP’s parliamentary group pushed back, saying it needed to ensure the heating law was economical and feasible for utilities and municipalities.

Wolfgang Kubicki, a deputy FDP leader who has repeatedly clashed with the Greens, said the decision by the constitutional court is a “deserved reward” for the party and accused it of putting “an inexplicable pressure into this procedure.”

--With assistance from Joe Ryan.

(Updates with lawmaker comments starting in sixth paragraph)