How did the United States support the Allies after Roosevelt's reelection?
The USA joined WWII after Pearl Harbor( 7th Dec 1941)
Before Pearl Harbor, FDR wanted the USA to join WWII on the side of the allies but he was unable to convince Congress. Weapons were exported to Great Britain but no military move was taken. After the Japanese attack, the USA declared war on the Axis(Germany, Italy and Japan)