this should not be a shocker to anyone, but iran will always exert a degree of influence inside iraq. just like the syria will always have influence on the politics of lebanon and the u.s. will always have influence on the politics of canada and mexico. bigger countries in wealth or population always exert influence on the internal politics of their neighbors. that's simply a fact of life.
so to the extent the bush administration is demanding that iran end its influence in iraq, he's on a fool's errand. the only realistic option is to try to change the kind of influence iran is having in iraq. but that would require talking to the iranians, something that bush has ruled out. which means that bush's plan to stop iranian influence on iraq will fail.
what we're seeing instead is a lot of bluster over bush's doomed plan, so that later he can blame whatever happens in iraq on iran.