British Tory leader David Cameron has been urged by Germany's chancellor Angela Merkel not to pull his MEPs out of the European People's Party (EPP) in the European Parliament.
Mr Cameron has made clear he will soon formally break the Euro-Tories' controversial political ties with the mainstream centre-right political bloc in Strasbourg, because it is too federalist for British Tory comfort.
But in a letter congratulating Mr Cameron on his election, Ms Merkel insists it is in the interests of both sides to keep the link.
"Great Britain and the British Conservatives are an indisputable element of European politics. In the EU we can work together on our common interests and convictions to safeguard individual freedoms, the regulation of the common market, as well as a strong transatlantic co-operation," she writes.
Mr Cameron is already facing a revolt from many of his 28 MEPs over his intention to end the alliance. Cast adrift, Tory fortunes in Strasbourg would depend on which of the various small independent political factions they chose to forge links with - if any.
Scottish Tory MEP Struan Stevenson, a vice-president of the EPP-ED group, has warned he will refuse to accept a Cameron decree to pull out of the group.
He has warned that severing the link would see the Tories searching for a new political berth of convenience - possibly joining a group of "non-aligned" MEPs - including French National Front leader Jean-Marie Le Pen, Alessandra Mussolini, granddaughter of the Italian dictator, and former UK Independence Party member Robert Kilroy-Silk.
The president of the Party of European Socialists, Poul Nyrup Rasmussen, said the controversy exposed deep splits in the centre-right in European politics.
"The EPP has been in danger of splitting for years. Now it is showdown time," said Mr Rasmussen.
"The question is, if the Tories leave, who will jump ship with them? Will it be a ragbag of free marketers and nationalists or will one of the bigger parties also abandon the EPP?" he asked.