Complex sentence: Wilson himself tried to get a third term in 1920, by deadlocking the convention; he deliberately blocked the nomination of his Secretary of the Treasury and son-in-law, William Gibbs McAdoo.
Split into simpler sentences: Wilson himself tried to get a third term in 1920, by deadlocking the convention. Wilson deliberately blocked the nomination of his Secretary of the Treasury and son-in-law, William Gibbs McAdoo.