Complex sentence: He had voted for Franklin D. Roosevelt in 1932, but quickly turned against him over Roosevelt's attempt to pack the Supreme Court, which had thwarted FDR's legislative agenda by striking down the National Industrial Recovery Act.
Split into simpler sentences: He had voted for Franklin D. Roosevelt in 1932, but quickly turned against him over Roosevelt's attempt to pack the Supreme Court. The court had thwarted FDR's legislative agenda by striking down the National Industrial Recovery Act.