Norbert Roettgen, head of the German parliament’s foreign affairs committee and a candidate to head Merkel’s Christian Democratic party, said the Nord Stream 2 pipeline needs to be stopped because completing it would reward rather than punish Russian President Vladimir Putin.

“After the poisoning of Nawalny we need a strong European answer, which Putin understands: The EU should jointly decide to stop Nord Stream 2,” he said Thursday on Twitter. “Diplomatic rituals are no longer enough.”

Merkel said tests showed “unequivocally” that Navalny was poisoned by a military-grade novichok nerve agent and called on the Russian government to provide answers. The substance was used in the March 2018 attempted murder of former Russian spy Sergei Skripal and his daughter on British soil, prompting a concerted expulsion of 150 Russian diplomats.

Merkel plans to consult with European Union and NATO allies to formulate a response in the coming days, but didn’t make a proposal.

Alexander Dobrindt, the deputy caucus leader and a member of the Bavarian branch of Merkel’s bloc, demanded new EU sanctions against Russia. There will have to be a “common European response to this deed,” the lawmaker said at a press briefing Wednesday, as well as “uncomfortable and serious” discussions between the Russian and German governments.

Before a special German armed forces laboratory confirmed Navalny’s poisoning with novichok, the chancellor decoupled the status of the Nord Stream 2 gas pipeline from the attack on the Putin critic. The project is a joint Russian-European economic venture and linking it to the Navalny case “isn’t appropriate,” she said on Friday.

The Nord Stream 2 consortium is led by Russia’s Gazprom PJSC. The group, which includes BASF SE’s Wintershall DEA unit and Austria’s OMV AG, has invested close to 8 billion euros ($9.5 billion) so far on the 745-mile pipeline. Even before the Navalny poisoning escalated tensions with Russia, the project was in limbo amid renewed efforts by U.S. senators to torpedo its completion.

Ralph Brinkhaus, head of the parliamentary caucus for Merkel’s bloc, raised doubts about whether it will now be possible to proceed with Nord Stream 2.

“We will have to see in the next few days what kind of responses we get and what discussions will take place,” he said. “But this is indeed a very serious case,” Brinkhaus said Wednesday.

After realizing his statement ran counter to Merkel’s position on Nord Stream, he rowed back, saying: “I didn’t construct a direct link between the Navalny case and Nord Stream, but just meant general German-Russian relations and what consequences this might have.”