When the United States joined the Allies, why did the Allies concentrate first on defeating Hitler?

While the
Japanese struck first, public support behind the war was easier to mobilize with Hitler in the
European Theatre.  The previous post was quite accurate in the tactical advantage and military
alliance forged with the Europeans to go after Hitler first and the Japanese later on in the
conflict.  The threat that Hitler posed was one where individuals in the position of power were
able to mobilize those fighting to focus their efforts.  Many felt that Hitler was the
motivating force behind the Japanese attacks and posed the greater threat to the notion of
"freedom" in the world. In attacking Hitler first, few figured Japan to be a threat to
stand on their own.   This, and the fact that our allies were facing immediate and pressing
challenges from Hitler above all else, made it quite easy for the United States to harness all
of their efforts in the European Theatre before the Pacific.