BRUSSELS—European Union countries are digesting a multitude of proposals from Brussels to curb soaring energy prices ahead of winter, including a planned Russian gas price cap that has raised concerns in some capitals.

European Commission President Ursula von der Leyen proposed measures on Sept. 7 to pull down rocketing gas and power prices ahead of winter.

They include an EU price cap on Russian gas, an EU-wide cut in electricity demand, and a windfall levy on non-gas generators.

EU ministers will discuss the measures on Sept. 9.

Their meeting is not expected to approve any policies, but should make clear which options have strongest support—giving Brussels a steer on what should make it into final proposals.

The plan to cap Russian gas prices has received a mixed response.

The Baltic states—longtime supporters of curbing Russian gas imports—are in favor, alongside countries that do not rely on Moscow for fuel, including Portugal, which mainly imports LNG from Nigeria and the United States.

The country’s environment minister told a national broadcaster late on Sept. 7 the price cap would help curb market speculation, which would also help countries that do not buy Russian gas.

Others have warmed up to the idea after Russia further slashed gas deliveries to the bloc last month, but warned that unity among EU members would be needed to make it happen.

“If there will be unity around this point, we will support this. If, on the other hand, it’s something which is difficult to stomach for some, we’ll have to look at it carefully,” a senior diplomat from one EU country said.

Brussels has not yet specified how it would design the price cap, but certain types of EU laws require approval from all 27 EU countries.

Some central and eastern European states are wary, fearing the measure could cut them off entirely from already dwindling gas supplies.

President Vladimir Putin said on Sept. 7 that Russia will stop supplying gas and oil to Europe if price caps are imposed.

Given the low volumes supplied to Europe—and thus, Moscow’s lower gas revenues—some countries suggested a price cap would not accomplish much and little impact on gas prices within the bloc.

“It wouldn't solve anything,” one EU diplomat said.

Russian gas pipeline deliveries on the three main routes to Europe have fallen by almost 90% since September 2021, Refinitiv data show.

European leaders have accused Moscow of “weaponizing” its energy supplies, while Russia has blamed the cuts on technical problems caused by Western sanctions over its invasion of Ukraine.