A confederation is a loose alliance of several smaller states that band together for the common defense. The Confederate States of America tried this experiment and failed because states had too much power over national affairs. If the USA did that right now, our Armed Forces would be decimated and smaller states would be defenseless. A separation of federal and state powers in a republic such as America isn't perfect, but the democracy has been intact for 150 years since the Civil War.
Confederation did not work during the civil war. A confederation is not feasible because of the present state of the country which includes two nationally acceptable and recognized political parties. The Confederation party did not fair well in slavery times and will not win against the Democrats and the Republicans.