However, essentially it is the European Commission who conducts the negotiations. Their job is to reach a consensus out of the countries’ different opinions that everyone would agree to. Since it is a joint approach of the G7 and the European Union, the USA (primarily) and the UK are also involved. That is the reason of the activity of the Americans and the phone calls to Tallinn and Warsaw.
Several months of diplomatic efforts are coming to an end. It was already known at the end of May that the European Union will impose sanctions on Russian oil and that from December 5, Russian oil cannot be brought to Europe by ships. In the meantime, the issue of the price ceiling was added, and that is what has dragged on. In the end, the price ceiling was left to the G7 (US, Germany, France, Japan, Canada, UK, Italy) to negotiate. Through the G7, it reached the European Commission and from there to the European countries.
Consensus is needed
In order for the oil price ceiling to work, it is necessary to get the whole West to agree. (Hungary and Bulgaria, which are dependent on the pipelines, were already exempted earlier; therefore they are not very active in price ceiling negotiations.) The question which certainly arises is: if the Europeans and the Americans are not willing to pay more than 50 dollars (hypothetical price) per barrel for Russian oil, why should India or Indonesia accept it? Why should third countries go along with the “Western” sanctions, and why shouldn't Russia sell oil to third countries for the old or higher price?