When you hear Conservatives bemoaning America's loss of power, prestige and leadership, the blame will be somewhere other than in themselves.
The problem is in full view on every Republican debate and and from the top down in the most recent Bush administration. NOT the previous Bush administration.
The reason the Roman Empire fell will be the same reason we eventually collapse. Rome went from city to state to ruler of the known world with an Army in which every citizen served. To be a senator, to be a noble, meant fighting for Rome. From the founding of America until the end of the first Bush administration, American leaders were men who served their country. Some were great soldiers, some just showed up, but everyone served unless, like Franklin Delano Roosevelt, they could not even walk.
The beginning of the end for Rome was when the nobility stopped serving in the Army. Further deterioration came when the Army went from being mostly Roman to mostly Gauls and Goths and others. Later the Army was really a mercenary Army. The Empire split. The Empire dissolved.
Among the more than 20 candidates of both parties, all of the actual veterans have either dropped out or are barred from the debate: Rick Perry is gone. Jim Webb, the only actual combat veteran, is gone. Lindsey Graham and Jim Gilmore were barred from the "kids table" debate on the eve of Veteran's Day.
At the center of the debate stage are Donald Trump with five deferments and Ben Carson with three. They actually dodged the draft and let someone else serve in their place. John Kasich also avoided the draft. The rest of the candidates simply chose not to serve.
When the leading citizens of the a country avoid military service and the poor and minorities and immigrants are overrepresented in the Army, then the reason for decline is clear. Draft dodgers like Rush Limbaugh can make up a thousand other reasons for America's decline, but Rome fell when its leading citizens acted just like America's leaders now.