Complex sentence: The Liberal Party of Charles Stewart, which had governed the province since its creation in 1905, was defeated by a surging United Farmers of Alberta, an agricultural lobby organization that was contesting its first general election.
Split into simpler sentences: The Liberal Party, which had governed the province since its creation in 1905, lead by Charles Stewart at the time of the election, was defeated by a very-new United Farmers of Alberta political party. The UFA was an agricultural lobby organization that was contesting its first general election.