BRUSSELS — The EU is bracing for national leaders to vent their concerns about its green agenda — and hoping it doesn’t turn into an outright rebellion.

On Thursday, the 27 heads of state and government will have their say on a new target for slashing the bloc’s planet-warming emissions by 2040, a core promise of Ursula von der Leyen’s second term as European Commission president.

It’s a critical balancing act for von der Leyen. She is looking for a way to appease the economic and political concerns of a growing number of EU members without allowing them to erode a set of stringent climate laws she built during her first five years leading the EU executive.

Von der Leyen and European Council President António Costa “are responsible for the success” of Thursday’s summit, said Linda Kalcher, director of the Brussels-based Strategic Perspectives think tank. “It’s in their interest to manage the debate well and avoid unravelling with leaders opening the Pandora’s box to weaken laws.” 

The discussion is meant to break a stalemate that is holding up an agreement on the new climate goal, but could just as easily lead to demands to weaken the policies designed to cut pollution. 

In an effort to preempt such demands, von der Leyen this week offered a slate of concessions — vowing to tweak existing climate laws to address governments’ economic concerns, but without substantially weakening the measures.

The question is whether that will prove enough. 

Searching for incentives

Von der Leyen has already spent much of her second term chipping away at green laws she proposed over the previous five years, slashing requirements for companies and promising more flexible rules. Those efforts have been balanced, however, with her desire to protect the core of the bloc’s mission to zero out climate-warming pollution by 2050.

Her proposed 2040 target also grants significant leeway to governments, even allowing them to outsource a portion of the required emissions cuts abroad.

To date, this approach hasn’t placated leaders. Ahead of Thursday’s summit, 19 countries were calling for even more deregulation from the Commission. A vocal contingent — including Poland’s Donald Tusk and Italy’s Giorgia Meloni — have made far-reaching demands that the bloc’s existing measures be weakened, in return for even considering supporting the 2040 goal. 

Leaders are not expected to spend much time discussing the actual target, although some countries that are unhappy with the Commission’s proposal — a plan to cut emissions by up to 90 percent below 1990 levels by 2040 — are bound to vent their frustration. 

Costa, who chairs the discussion, has instead asked leaders to discuss how the bloc can marry climate efforts with economic competitiveness. 

Both he and von der Leyen were unwilling to debate the target itself, according to one diplomat from an EU country and a European official briefed on the preparations for Thursday’s summit. 

But his invitation to leaders to outline their conditions for supporting the 2040 target risks “a Christmas tree” effect, the diplomat said, where each leader hitches their own pet policies to the target. 

The diplomat, who was granted anonymity as they were not authorized to discuss the summit, added that French President Emmanuel Macron — who pushed for the leaders’ debate — was seen as pivotal. 

The Commission has offered France significant concessions for backing the 2040 target, including a large hike on steel tariffs. The attitude Macron brings to the summit could make or break the talks, the diplomat warned.

Other leaders are expected to push to weaken existing rules as a tradeoff for backing the target. Poland hopes to delay a carbon tax on fossil fuels used in transport and heating, while Italy has requested changes to the EU’s combustion-engine phaseout. 

Others want reassurances about future policies. France would prefer to avoid a fresh renewable energy target that sidelines its nuclear power fleet, and Germany wants a less onerous decarbonization path for its heavy industry. 

The details of what is agreed will be key. “It depends on the nature of the tweaks,” said Simone Tagliapietra, a senior fellow at the Bruegel think tank in Brussels. 

Those might simply make compliance easier, or conversely could weaken the bloc’s climate efforts. “But overall, yes, we are entering dangerous territory.”