Complex sentence: Since the 1980s, he had advocated the unification of the right-wing groupings into a single large party, but it was Chirac who managed the feat, with the creation of the Union for a Popular Movement in 2002.
Split into simpler sentences: Since the 1980s, he had advocated the unification of the right-wing groupings into a single large party. Chirac realized this with the creation of the Union for a Popular Movement in 2002.