Some German government members have voiced unease about Merkel's backing for Sarkozy.
"A German head of government who campaigns for a president who has his back to the wall is damaging the relations between Germany and France," Juergen Trittin, a former environment minister and parliamentary leader of the opposition Greens, told daily Ruhr Nachrichten's Tuesday edition.
Sarkozy is near certain to announce soon that he's running for France's elections in April and May. But he lags in polls well behind Socialist Francois Hollande, who responded derisively to Merkel's lobbying for Sarkozy.
"It's a rough task she is giving herself. It won't be easy to convince the French" that Sarkozy is worthy of their vote, Hollande said at a campaign event in Dijon. "And the fact that Nicolas Sarkozy needs Madame Merkel says a lot about his situation."
"For me, my only criteria are the French people. That's who I'm turning to for the presidential election. I don't need anyone else other than the vote of the French," he said.
Baetz reported from Berlin. Cecile Brisson in Dijon, France and Masha Macpherson in Paris contributed to this report.
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