What was the main reason that federalists supported ratification of the constitution? *

The Federalist Papers were written in support of ratifying the Constitution, and expressed well the views of the Federalists.  In those essays, Alexander Hamilton, James Madison and John Jay wrote in favor of the Federalists' position on the need for a strong federal government, advocating ratification of the US Constitution which would give the federal government significantly more powers than the Articles of Confederation had.

The essays that came to be known as The Federalist Papers originally appeared in serial fashion in several newspapers.  85 essays total were then published in a 2-volume set in 1788, under the title, The Federalist: A Collection of Essays, Written in Favour of the New Constitution, as Agreed upon by the Federal Convention, September 17, 1787.

d) the constitution rights of native americans and their right to self-government on reservations