"Most of the initiatives to resettle refugees in underdeveloped areas proved impossible, met substantial resistance abroad, or developed very slowly partly because of resistance by the Department of State," the Center for Jewish History says in a statement about the book.
The claim that Roosevelt actively sought ways to help Jews escape Europe before the war began in 1939 challenges the widely accepted view that he ignored warnings of Adolf Hitler's plan to exterminate them.
One example supporting that theory was the government's refusal to allow the SS St. Louis, a German ship carrying 900-plus Jewish refugees, to dock at a U.S. port in 1939. Instead, the ship was sent back to Europe where many passengers later perished in Nazi camps.
The book is based primarily on diaries of James G. McDonald, the League of Nations' top official concerned with refugees from Nazi Germany in the mid-1930s.
"In tracking him, we stumbled on other new evidence about FDR's role," Richard Breitman, one of the book's three editors, told a news conference on Friday.
In 1935, McDonald quit the League of Nations post to protest lack of support on the issue and later headed a committee advising Roosevelt, while also pressing for changes in U.S. immigration laws. In 1948, he became the first U.S. ambassador to the new state of Israel.
McDonald's diaries, owned by his family, were analyzed by the United States Holocaust Memorial Museum in Washington, D.C., and provided to a team of editors headed by Breitman, an American University history professor and Holocaust scholar. The team's resulting book is published by Indiana University Press.
The State Department raised bureaucratic obstacles to immigration, through denial of visas and in alloting quotas for refugees, and along with Congress, resisted funding conferences or other initiatives on refugee resettlement. The State Department also stifled public release of reports about genocide. In 1942 it received but declined to release a report detailing Nazi plans to wipe out Europe's Jews, according to the Holocaust museum.
McDonald's writings "provide a unique perspective on the workings of Nazi Germany and the American reaction to them," said Holocaust museum research director Paul Shapiro. He called the preservation of this evidence "especially urgent" as that generation dies off.
Scholars disagree as to whether "Refugees and Rescue" sheds important new light.
Deborah E. Lipstadt, a professor of modern Jewish and Holocaust studies at Atlanta's Emory University, said it would "change the consensus" about FDR's role.