Complex sentence: The previous legislative election in 1951 had been won by the Third Force, a coalition of center-left and center-right parties, but when faced with the colonial problem, the governments had gradually moved towards the right.
Split into simpler sentences: The previous legislative election, in 1951, was won by the Third Force, a coalition of center-left and center-right parties. But little by little, faced with the colonial problem, the governments moved towards the right.