note: these points concern partisanship as it was manifested mainly from the nation's founding until the conclusion of the Second World War.  Here, a note from Wikipedia's entry on the US Democratic Party's origins:

" Origins of the Democratic Party: 1792-1828
The Democrats trace their roots to the Democratic-Republican Party established by Thomas Jefferson in the 1790s. This party arose from opposition to the policies of the ruling Federalists, which advocated a strong central government and and a republic governed by elites. Members called it the "Republican Party" after the principles of republicanism to which they were devoted, although the party is referred to as the Democratic-Republican Party to distinguish it from the modern Republican Party, with which it has not connection. The Democratic-Republicans favored France over Britain in the wars of the French Revolution that broke out in 1793 and continued until the final defeat of Napoleon in 1815. They saw the independent ("yeoman") farmer as the ideal exemplar of virtue, and distrusted cities, banks, and factories. They were strong in the South and West, and weakest in New England."

" The Democratic-Republican Party won control of the presidency and congress in 1800, and managed to eliminate the Federalists as serious rivals by the end of the War of 1812. After 1816, the remnants of the party split into factions. War hero General Andrew Jackson of Tennessee, emerged as the leader of the faction that, after he was elected president in 1828, became the Democratic Party."

http://en.wikipedia.org/wiki/Democratic_Party_%28United_States%29#Origins_of_the_Democratic_Party:_1 792-1828

    my introductory part continued:

 While it's true that the Constitution's meaning was, from the very beginning, the subject of disagreement, it was expected to be thus.  An institution, as a separate branch of the national government, the Supreme Court, was expressly created by the terms of the Constitution itself for the purpose of arbitrating and ruling on « cases and controversies » arising from disagreements about the application of the Constitution and about disputes between the several states.  

    This, at any rate, is or was the popularly-accepted and idealized myth even if the historical facts are, in reality, much more complicated and disputable.  Americans constituted a single people forged  from widely divergent, though mainly European, nations and experiences.   As Americans, what they shared, at a minimum, was the desire to leave all that behind and become part of something new to which they'd all contribute their futures.

    We may even summarize the basic principles as follows:

    A legitimate government is constituted by the expressed and freely-given consent of those adult citizens over whom it may exercise legal authority.  Its powers are enumerated--that is, limited  --and usually set out in a written founding-charter, formally adopted by a majority of the citizenry or their authorized delegates.  The government exercises its authority through duly constituted institutions which are managed by publicly-elected officials or their appointees, who must  regularly submit themselves to the public's election by free and fair secret balloting at an appointed time and place.  Certain civil rights are to be respected as inviolable for all regardless of circumstances and protected from infringement,  no matter how large a majority of the public might favor that  infringement--including the right to public assembly and speech, to vote, to be secure from arbitrary or unwarranted searches, seizures or arrests and, when arrested upon a warrant or upon cause, to be afforded the right to a fair and speedy public trial at which one is entitled to be defended and to confront and question one's accusers before a jury of one's peers, the jury being free to determine by its  sole discretion, the question of guilt--innocence being presumed until,  by formal standards of judicial proof, guilt is established to the satisfaction of the jury in a majority or unanimous vote.

    The parties of Republicans and Democrats, then, were in appearance and in fact not so very different in their basic political philosophies--if they can even be said to have had one for more than election campaign's purposes.  Wherever there is a desirable prize to be won--in this case, the exercise of political power on the national level--we shall find two or more contenders vying for it.   Where Democrats and Republicans differed was in the personalities which belonged to their party and in these individuals' talents, in their abilities to effectively manage the public's affairs--or, that is, at least to persuade the public of that in an election campaign.

    Americans determined how to vote according to their feelings about such things as whether taxes were supportable or not;  whether the roads were maintained and the schools properly administered; whether businesses and farms were able to prosper in the nation's economy; whether public affairs were tolerably or intolerably corrupt; and,  of course, whether the public morals were paid adequate lip service and whether or not those in the public's view set a not-too-scandalous example for children.   The ideological details of politics were the concern of a relative few, notably lawyers, writers, scholars, some politicians, clergy and, of course, the militant fringe among the poor and oppressed.  Thus, party fortunes waxed with economic booms and waned with economic busts or with what voters foresaw as imminent in boom or bust.

 [ So, please help pick this apart: where would you revise this to improve sense and historical accuracy?  What assumptions are here which you find false or inaccurately presented?  Note that I won't have access to Robert F.'s suggested reading for some little while and this can't therefore reflect the points in that book. ]