Domestic Policies and Realism

Someone brought up the point in class that domestic policies have a dramatic effect on a nation's foreign policy. This is the key element of a series of flaws that realism simply cannot provide for with its take on the international system. As the debate rages on in America about whether the War in Iraq is truly a matter of national security or simply a large waste of lives and resources, we may very well have a president and Congress in 2008 who are willing to break back our troops from that theater. Will it be because everyone suddenly realized that the War isn't in our vested interests and doesn't pertain to our Fundamental Continuity or Physical Survival? No, it will be because the domestic politics of our country would be changed with a new election. Every party brings its own separate views to the table and every new election can bring a change in a country's views of the international system. I feel this is just one of the many factors that realism doesn't take into account, making it a slightly flawed theory (though not altogether useless).