In my opinion, the Lend Lease Act is an even great contribution by Roosevelt than anything, including the New Deal.
The Lend Lease Act enabled the US to get on a war footing prior to the United States' entry into World War II.
Without the Lend Lease Act, the US would have been attacked in December of 1941 and would have found itself without the tools needed to respond.
The US likely would have lost to Japan in the Pacific as a result.
