Complex sentence: Once a liberal Democrat, Professor Kagan changed his views in 1969 and became one of the original signers to the 1997 Statement of Principles by the neoconservative think tank Project for the New American Century.
Split into simpler sentences: Once a liberal Democrat, Professor Kagan changed his views in 1969. He was one of the original signers of the 1997 Statement of Principles by the neoconservative think tank Project for the New American Century.