Complex sentence: He was a member of the Socialist Party from 1993 to 2007; he is mayor of Donzère since 1995 and was "député" for the Drôme between 1997 to 2007 (he did not stand for re-election in 2007).
Split into simpler sentences: He was a member of the Socialist Party from 1993 to 2007. He has been mayor of Donzère since 1995 and was the "député" for the Drôme between 1997 to 2007 (he did not stand for re-election in 2007).