What are the three main groups that researchers theorize may have the biggest impact on domestic policy?

representative government

explanation:

american revolution: major events leading to declaration of independence. 1765-1766; tax introduced on legal documents to pay for defense of colonies. 1766: stamp act repealed after merchants protesting due to their goods not being bout and officials being threatened.

abraham lincoln  (february 12, 1809  – april 15, 1865) was an american statesman, politician, and lawyer who served as the 16th  president of the united states  from 1861 until  his assassination  in april 1865. lincoln led the nation through the  american civil war, its bloodiest war and its greatest moral, constitutional, and political crisis.[2][3]  he preserved the  union,  abolished slavery, strengthened the  federal government, and modernized  the u.s. economy.