Only Congress can declare war. Presidents can ask Congress to declare war . The presidents who made such a request and had it granted were James Madison (against Great Britain), James Polk (against Mexico), William McKinley(against Spain), Woodrow Wilson (against Germany and allies) and Franklin Roosevelt (against Japan and allies)
Only Congress can declare war. The president can ask Congress to declare war. Two modern Democratic President, Woodrow Wilson and Franklin Roosevelt, asked Congress to declare war and were granted their request. James Polk, also asked for a declaration of war and he belonged to the (Jacksonian) Democratic Party, which was not really the same as the modern Democratic Party.