From No. 51 of The Federalist Papers, which branch of government did Madison think would be the weakest?Please help!

Federalist 51 which was written by James Madison concerns
several important principles on which the federal government is based, separation of
powers and checks and balances.  Madison believes that the legislative branch is the
most powerful.  He states “In republican government, the legislative authority
necessarily predominates.”  The legislative branch is the one closest to the people in a
republic and therefore would wield the most power.  He probably believes this because in
his own state of Virginia, the legislative branch dominated.  To keep the legislative
branch from becoming too powerful, he believed that “An absolute negative on the
legislature appears, at first view, to be the natural defense with which the executive
magistrate should be armed.” That is, the executive branch should have veto power over
the legislative branch.  But because the legislative branch can wield so much power,
more needs to be done. The legislative branch should be further divided (into a House
and Senate) and these two houses have different means of election.  In the original
Constitution, the House was elected directly by the people and the Senate was chosen by
state legislatures.