Why did America's founders adopt constitutional democracy as the U. S. political system?

Because the American founders wanted to mirror or to reflect same governance with the Great Britain that is why the adopt constitutional republic over the United State political system. The founders became very worried about the situation in the United States, they set it up to form a representative of a constitutional republic.

Explanation:

an interest group is an organization whose members share common concerns, and try to influence government policies that impact those concerns. elected officials frequently complain about the influence of "special interests" on american politics.