And from the following, some Americans officials did try within the constraints they faced:
Setting the record straight on the S.S. St. Louis, 75 Years Later, Post and Courier, Robert Rosen, May 27, 2014.
http://www.postandcourier.com/article/20140527/PC1002/140529469
' . . . The point man on the St. Louis was Henry Morgenthau, Roosevelt's Jewish Secretary of the Treasury and a major contributor to the JDC. Morgenthau worked behind the scenes with the State Department, leaders of the JDC and others to see to it that none of the St. Louis passengers returned to Germany. The American Consul-General in Havana, Coert DuBois, and Ambassador J. Butler Wright, worked closely with the JDC. Secretary of State, Cordell Hull, was involved and Ambassador Joseph P. Kennedy lobbied British authorities. The JDC put up substantial money to guarantee that the passengers would not become a burden in their new places of refuge. . . '