JFK's father was our ambassador to the UK, 1938 to 1940. He was branded as an isolationist, appeaser, anti-Semite, and coward.
Appeasement - Kennedy rejected the belief of Winston Churchill that any compromise with Nazi Germany was impossible. Instead, he supported Prime Minister Neville Chamberlain's policy of appeasement. Throughout 1938, while the Nazi persecution of the Jews in Germany intensified, Kennedy attempted to arrange a meeting with Adolf Hitler. Shortly before the Nazi bombing of British cities began in September 1940, Kennedy once again sought a personal meeting with Hitler without the approval of the U. S. Department of State, in order to "bring about a better understanding between the United States and Germany".
Cowardice - Kennedy and his family retreated to the countryside during the bombings of London by German aircraft in World War II. This move prompted Randolph Churchill to say, "I thought my daffodils were yellow until I met Joe Kennedy".
Plenty of examples out there - don't ask for a source.