By approval, I think you mean by the delegates from each state had approved it. The problem was that the states themselves had to approve it. That seemed like a cumbersome process, but you have to remember that democracy works on the will of the people and each state had to ratify it keeping in mind that there were still problems: it was not a slam dunk.
nine states had to ratify, or given consent to the Constitution
Well first, it had to be ratified by states. Second, once that happened, it had to actually be enforced and accepted by the states. It was a more complex process than just signing a piece of paper.
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