Reuters After publicly throwing her weight behind Nicolas Sarkozy's re-election campaign at the start of the year, Germany's Angela Merkel and her advisers are quietly preparing for the possibility that they may have to do business with his Socialist challenger. The tone in Berlin has shifted in recent weeks from one of unwavering support for Sarkozy to annoyance with his shift to a more populist campaign and his abrupt reversal on the role Merkel herself will play in his drive for a second term. The French president's UMP party won her agreement at the start of 2012 to campaign with him in France, only to drop that idea weeks later, prompting an incensed Merkel to complain about Sarkozy's “erratic behavior”, aides say. German Foreign Minister Guido Westerwelle broke the silence in Berlin last week, denouncing Sarkozy's threat to pull France out of the European Union's open-borders Schengen zone. Despite the irritations, Sarkozy remains Merkel's preferred choice, in part because he has backed Germany's push for tighter fiscal discipline in Europe. But at the same time, concerns about Sarkozy's front-running rival for the presidency, Francois Hollande, seem to have dissipated. Now, the talk in Berlin is of a “charm offensive” if Hollande wins to minimize any hard feelings about Merkel's strong public backing for Sarkozy and her refusal to meet the Socialist before the two-round French vote in April and May. Initial anger over Hollande's vows to renegotiate the euro zone's “fiscal compact” — a new set of rules on budget discipline that Merkel pushed on her partners — has eased somewhat. Now some German officials are dismissing it as nothing more than “campaign talk”. One senior official even suggested that new language on growth-supporting measures could be added to the fiscal compact to appease Hollande if he beats Sarkozy, though others close to Merkel have ruled out any tampering and said post-facto tweaks to accommodate a new leader would set a dangerous precedent. “We're really not worried about Hollande,” the senior official said. “This is an election campaign. He has to come up with something to distinguish himself from Sarkozy.” As for Hollande's insistence on growth-boosting measures to complement the German push for stricter budget discipline, the official said he could envision “principles being agreed with the French” if the Socialist comes out on top. Merkel's spokesman Seibert said Merkel and Sarkozy had worked extremely closely together, developing a “high degree of mutual trust in a very critical period for Europe.” But he also made clear that Merkel would try to develop the same close rapport with Hollande were he to defeat Sarkozy. Polls give Hollande a high lead in a head-to-head second-round contest. __