PARIS/BERLIN Jan 31 (Reuters) - By enlisting Germany's Angela Merkel to help his bid for reelection, French President Nicolas Sarkozy has put Europe at the heart of his campaign. Merkel's decision to back him suggests nervousness on her part about a change of leadership when the French-German partnership is driving euro zone policy.
Both leaders have played down the move. But with Socialist Francois Hollande leading polls, Merkel's camp worries about losing the momentum she has built with Sarkozy in tackling Europe's debt crisis and the prospect of France being run by a man whose campaign one Merkel MP termed a "leftist anachronism".
Merkel's backing for Sarkozy was announced by her Christian Democrat (CDU) party after a speech by its second-in-command, Hermann Groehe, at a meeting of Sarkozy's UMP party in Paris on Saturday. Groehe said Hollande's policies would weaken Europe.
"The upcoming election in France is not just decisive for that country, but for the successful resolution of Europe's common challenges," he later told Reuters.
UMP lawmaker Olivier Carre called Merkel's support "highly symbolic". "Europe will be at the heart of the campaign. It's also natural that after working together for three years they stand together to defend their ideas."
Hollande's spokesman Manuel Valls warned the UMP not to "hijack" the German relationship for political ends.
Merkel's appearances before the first round of voting on April 22 is aimed at underlining the importance of the "Merkozy" relationship to Europe. "The French election affects everybody in Europe," said Elmar Brok, a CDU member close to Merkel.
UMP insiders say the push to involve Merkel came from Sarkozy himself. The UMP's head, and a key architect of its 2012 campaign, Jean-Francois Cope, would not be drawn into detail on the issue in a meeting with Reuters reporters on Monday, but noted that Merkel is "highly respected in France".
Indeed, a Harris Interactive opinion poll conducted in August found that respondents trusted Merkel much more than Sarkozy to resolve the economic turmoil in the euro zone.
"Merkel is saying publicly that she prefers Sarkozy, because she knows his capacity and of course we can only celebrate that, it's very satisfying for us," a separate UMP official said.
MISGIVINGS IN BERLIN
Twelve weeks before the ballot, Sarkozy is trying to show he is best-placed to lead France out of economic difficulty and believes his closeness to Merkel will please conservative voters. His strategy of not launching his re-election bid until close to a March 16 deadline ties in with his belief that his best chance of holding onto power is as an active president, busy dealing with the euro zone crisis, political analysts say.
"In terms of credibility, this is a little point scored for Sarkozy," said Jean-Thomas Lesueur, head of the Paris-based Institut Thomas More think-tank, regarding Merkel's backing.
"Merkel is seen as a serious person, Germany is well-managed and holding up in the storm. Being close to her could count."
Sarkozy won plaudits early in his term for his response alongside Merkel to the 2008 financial crisis. Since then he has worked hard to further burnish his diplomatic credentials, taking advantage of holding last year's G20 presidency to make a joint TV appearance with U.S. President Barack Obama.
German conservative Andreas Shockenhoff, head of a Franco-German parliamentary group, said the CDU's aim was to help Sarkozy "defend Europe and the euro" against a Socialist platform he described as "a completely anachronistic leftist ideological programme".
German sources say it was the UMP that wanted Merkel to show her support, but put it in the context of concern in Berlin that having to deal with a newcomer could slow up resolving Europe's debt crisis. "If Hollande wins the French election, it won't make things impossible, but they'll be more difficult," a senior German source told Reuters.
Hollande promises to be fiscally responsible and differs little from Sarkozy in his overall Europe policy, but he wants to renegotiate the new treaty currently being fleshed out by European Union leaders to add clauses on growth and welfare.
Analysts sense Berlin is concerned over a recent speech by Hollande in which he declared war on the world of finance, widely seen as a tactic to rally leftwingers behind him in the first-round vote.
Hollande's main impact on bilateral relations would be that he wants to mark a break with a period where Berlin and Paris led decision-making for the 17-member euro zone bloc, and return to wider meetings where decisions have more input from European institutions and national parliaments.
"The French must understand this election is not about domestic political issues," said Ulrike Guerot, senior policy fellow in Berlin for the European Council on Foreign Relations.
"Merkel is quite right to go on the offensive in what is a trans-national election campaign."
Hollande's aides insist he would bring a seamless transition for the Franco-German machine, but Merkel has thus far declined his invitations to meet. Conservatives concede Hollande's personality could be a better match for Merkel than the hot-blooded Sarkozy, but say he could upset a fruitful partnership.
"Hollande's weakest point is that he is totally disconnected from the reality of the world today," Cope told Reuters.
"There is no other solution than to imagine a 'G2', Germany and France. We are bound to do this especially now as we build a new kind of European governance and strategy," he said.
Sarkozy's idea of involving Merkel could backfire if voters object to her presence as foreign interference. Economic policies promoted by Germany are not universally popular.
Jacques Reland of the Global Policy Institute said many voters could be hostile to the idea of going down a German path of lower wages and less social protection.
Sarkozy was accused by the left and centre last year of ceding to pressure from Germany to give up budget sovereignty to Brussels. The loss of France's AAA credit rating with Standard & Poor's, putting it a peg below Germany, has also increase sensitivities about perceived German dominance.
"Even if the Franco-German relationship is strong, for the French it's not for other countries to tell them what to do," said Stephane Rozes, head of political consultancy Cap.