John Adams, second president of the United States, said, in a letter to Jonathan Jackson on Oct 2, 1789…
There is nothing which I dread so much as a division of the republic into two great parties, each arranged under its leader, and concerting measures in opposition to each other. This, in my humble apprehension, is to be dreaded as the greatest political evil under our Constitution.
George Washington said, in his Farewell Address of Sept 19, 1796…
I have already intimated to you the danger of Parties in the State… Let me now take a more comprehensive view, and warn you in the most solemn manner against the baneful effects of the Spirit of Party generally.
This spirit, unfortunately, is inseparable from our nature, having its root in the strongest passions of the human Mind. It exists under different shapes in all Governments, more or less stifled, controlled, or repressed; but, in those of the popular form, it is seen in its greatest rankness, and is truly their worst enemy.
The alternate domination of one faction over another, sharpened by the spirit of revenge, natural to party dissension, which in different ages and countries has perpetrated the most horrid enormities, is itself a frightful despotism. But this leads at length to a more formal and permanent despotism. The disorders and miseries which result gradually incline the minds of men to seek security and repose in the absolute power of an individual; and sooner or later the chief of some prevailing faction, more able or more fortunate than his competitors, turns this disposition to the purposes of his own elevation, on the ruins of Public Liberty.
Without looking forward to an extremity of this kind (which nevertheless ought not to be entirely out of sight), the common and continual mischiefs of the spirit of party are sufficient to make it the interest and duty of a wise people to discourage and restrain it.
It serves always to distract the Public Councils and enfeeble the Public administration. It agitates the community with ill-founded jealousies and false alarms, kindles the animosity of one part against another, foments occasionally riot and insurrection. It opens the door to foreign influence and corruption, which finds a facilitated access to the government itself through the channels of party passions. Thus the policy and the will of one country are subjected to the policy and will of another.
There is an opinion that parties in free countries are useful checks upon the Administration of the Government and serve to keep alive the spirit of Liberty. This within certain limits is probably true; and in Governments of a Monarchical cast, Patriotism may look with indulgence, if not with favor, upon the spirit of party. But in those of the popular character, in Governments purely elective, it is a spirit not to be encouraged. From their natural tendency, it is certain there will always be enough of that spirit for every salutary purpose. And there being constant danger of excess, the effort ought to be by force of public opinion, to mitigate and assuage it. A fire not to be quenched, it demands a uniform vigilance to prevent its bursting into a flame, lest, instead of warming, it should consume.
It is important, likewise, that the habits of thinking in a free Country should inspire caution in those entrusted with its administration, to confine themselves within their respective Constitutional spheres, avoiding in the exercise of the Powers of one department to encroach upon another. The spirit of encroachment tends to consolidate the powers of all the departments in one, and thus to create, whatever the form of government, a real despotism. A just estimate of that love of power, and proneness to abuse it, which predominates in the human heart, is sufficient to satisfy us of the truth of this position. The necessity of reciprocal checks in the exercise of political power, by dividing and distributing it into different depositaries, and constituting each the guardian of the public weal against invasions by the others, has been evinced by experiments ancient and modern; some of them in our country and under our own eyes. To preserve them must be as necessary as to institute them. If, in the opinion of the people, the distribution or modification of the Constitutional powers be in any particular wrong, let it be corrected by an amendment in the way which the Constitution designates. But let there be no change by usurpation; for though this, in one instance, may be the instrument of good, it is the customary weapon by which free governments are destroyed. The precedent must always greatly overbalance in permanent evil any partial or transient benefit, which the use can at any time yield.
–George Washington, from the Farewell Address of Sept. 19, 1796 in: The Writings of George Washington, pp. 969-71 (Library of America ed. 1997)