PARIS - Nicolas Sarkozy said he would change the tax system to help companies and pledged on Sunday to win back National Front voters one-by-one in his first televised interview since announcing his return to French politics.The former president, who is seeking the leadership of the main rightist UMP party ahead of the 2017 presidential race, avoided giving policy details but sought to reassure companies and voters that he had heard their concerns."Today, global growth has returned to close to 4 percent, Germany is prospering, Europe is not in crisis, and yet we continue to stagnate and have rising unemployment. Why? Because our model must be completely restructured," he said in the interview on France 2.Sarkozy said the only question that mattered was to find a tax system that would allow businesses to create growth and jobs, and that would stop young people leaving France because they feel they cannot succeed at home."If you tax people and companies in France more, how can you expect them to be competitive? If companies lose market share, how can you expect unemployment not to rise? That's the key," he said. "What counts is giving our businesses the chance to gain market share."Sarkozy ended months of speculation on Friday when he announced his political comeback with a message on Facebook, saying he was ready to take charge of the opposition UMP party, riven by rivalry since he was ousted from power in May 2012, opening the possibility of a return to the Elysee Palace in 2017.