Merkel to join Sarkozy on campaign trail for French presidential election Despite outward signs that they get along well, Angela Merkel and Nicolas Sarkozy are not believed to be the best of friends. Eyebrows are being raised across Europe after Angela Merkel pledged to join Nicholas Sarkozy on the campaign trail in his bid to be re-elected French president later this year. In an unusual - and potentially risky - move, the German chancellor promised to go on the stump with her Gallic counterpart in an attempt to keep him in the Elysée. Hermann Gröhe, general secretary of Merkel's Christian Democratic Union (CDU), confirmed over the weekend that she would "actively support Nicolas Sarkozy with joint appearances in the election campaign in the spring." While it is not uncommon for certain world leaders to campaign on behalf of friends in neighbouring countries - Vladimir Putin has often vigorously supported candidates in former Soviet states - European politicians have generally adhered to an unwritten pact not to interfere with elections in other member states. They may support each other on certain issues - former German chancellor Helmut Kohl famously appeared on French TV alongside François Mitterand ahead of a referendum on France joining the euro - but to board their battle buses and speak at their rallies seems a new step, said Ulrike Guérot, an expert on Franco-German relations at the European Council on Foreign Relations. But, she said, it is likely to become ever more common as European leaders build a "transnational democracy." Anke Hassel, professor of public policy at the Berlin-based Hertie School of Governance, said it was very unusual for a serving European leader to campaign for an international colleague's re-election. "I cannot think of another example," she said. She too believes such cross-border support could soon be commonplace. I think we are in a profound period of change. Things are really being stirred up with the signing of the new fiscal treaty. This is the first step towards a much deeper integration on the political side of things. In these times of crisis, Merkel appears to be rewriting the "gentleman's rules" of what is largely still a boys' club. In October, she phoned the Italian president, Giorgio Napolitano, allegedly to "gently prod" him into getting rid of Silvio Berlusconi. The call, revealed in the Wall Street Journal after Berlusconi's defenestration, caused outrage in Italy. One Italian newspaper even ran a front page proclaiming "The Lard Arse Did It," a reference to Berlusconi's uncharitable nickname for his German counterpart. He allegedly prefixed the insult with "unfuckable." The strength of the endorsement is surprising for more personal reasons. Though the French and German leaders have been getting along better as the euro crisis bites deeper, the pair are far from the best of friends. At a gala in Frankfurt before Christmas marking the departure of the head of the European Central Bank, Jean-Claude Trichet, Sarkozy allegedly made ungentlemanly remarks about Merkel's fondness for cheese. Merkel's surprise announcement caught Paris on the back foot as Sarkozy, also of the centre-right, has yet to officially declare his candidacy for the election, which will take place over two rounds on 22 April and 6 May. "I did not know she voted in France," the French president said in an interview with multiple television channels on Sunday evening. Kassel, however, said she did not believe Merkel would have endorsed Sarkozy without first seeking his consent. At an election meeting of Sarkozy's UMP party in Paris on the weekend, Gröhe is said to have declared that the CDU are convinced Sarkozy "is the right man in the Elysée "now and in the future," the Süddeutsche Zeitung reported. We need a strong France with a strong president in charge. That person is our friend Nicholas Sarkozy," said Gröhe. He criticised Sarkozy's presidential rival, the Socialist François Hollande, who travelled to Germany before Christmas to offer comradely support to the Social Democratic Party (SPD), Merkel's main domestic rival. The Socialists are stuck in their dreams of the past. All they are doing is bringing out dusty concepts and wealth distribution fantasies from their moth-ridden policy cupboard," said Gröhe. None of Hollande's "hitherto vague pronouncements" offered a solution to the pressing problems of our time, he added, citing his proposal to lower the age of retirement. Merkel's endorsement could help Sarkozy, if polls are to be believed. One recent survey carried out on behalf of the French newspaper Le Monde suggested that more French people trusted the German chancellor than their own president. By allying herself so clearly with Sarkozy, however, Merkel is also taking a risk. After her support for him became public, the SPD immediately insisted she follow France's lead and introduce a so-called Tobin tax. In his interview on Sunday, Sarkozy announced a 0.1% levy on all financial transactions in France, which he said would generate €bn (£800m) of new income and cut his budget deficit. If Hollande wins, Merkel will have some making up to do.