This is a good question. First, some clarification: political parties in Washington's day weren't nearly as formal as they would later become. They were much more informal alliances, in that there weren't nominating conventions, or formal party leaders in Congress who would "whip" the vote, or party caucuses that necessarily formed majorities and controlled debate. That isn't to say there weren't partisans—there definitely were—but they operated much differently at the time. For example, well into the 19th century, parties operated mostly on platforms consisting of economic principles, while slavery, social issues, and other issues quite often crossed party lines and were decided along more geographical or "sectional" lines.

Anyway, while there were others like Madison who gave a little bit of cover to the idea of bipartisanship and nonpartisanship, even he would admit that factionalism and partisanship were a rather natural outcome of politics. George Washington was far and away the most outspoken critic of partisanship in the early years of the United States.

There are two ways of looking at Washington's view, and what he really envisioned. One I'll call the "Ketcham view" based on Ralph L. Ketcham's book Presidents Above Party: The First American Presidency, 1789-1829. The other I'll call the "Phelps view" based on Glenn A. Phelps' article "George Washington and the Paradox of Party", published in Presidential Studies Quarterly.

Both agree on the fundamental facts, that Washington entered the presidency truly believing that the President should be "above party". He should act as a sort of referee between competing ideas and then pick the best one. As Phelps points out, the phrase "impartial chief magistrate" is "a recurring one in his letters" and correspondence.

So how did Washington envision this working at the Congressional level, or among his Cabinet? Quite possibly, he thought it should work a lot like the Virginia House of Burgesses, where he'd started his career, and had served before the tensions that led to the Revolutionary War broke out. In his book Political Parties Before the Constitution, author Jackson Turner Main describes Virginia's politics before the Revolution as the least contentious in any of the colonies, characterized by "stability, continuity, [and] consensus":

"...[T]he [Virginia] colony's politics concentrated on the House of Burgesses's successful struggle for autonomy and the westward advance against French and Indians. Internally, Virginia gives the appearance of unity: the Burgesses certainly contained no disruptive elements or basic divisions until a few years before Independence. The reason, as is well known, lay in the unchallenged dominance of the planter elite, who...remained unified by a community of interest and ideas, and the governor never became strong enough to consistently drive a wedge into this solid front. Far from producing parties, Virginia scarcely produced factions.

"To some extent this serene uniformity changed after 1760 because of the Two Penny Act and the rise of Henry, the Robinson affair, which called into question the honesty of the elite, and the division of opinion concerning the resistance to England. These events set the stage for the postwar divisions that culminated in the 1790s."

This uniformity in political thought, writes Main, was accomplished because there was a uniformity in background among the legislators. They were nearly all wealthy planters, farmers, and lawyers who came from wealthy and landed families, and mostly had common political interests:

"During the colonial period at least four-fifths of the men in the House of Burgesses owned large estates. About 70 percent were primarily farmers, and two-thirds of the rest also owned plantations. Most (conceivably all) held slaves, and close to half belonged to the famous First Families—relatively few can be termed self-made. Almost all were Anglicans, and in general they seem much of a piece culturally; the exceptions exerted little political influence. Most historians agree that Virginia's internal political controversies are best described as factional...

"Independence brought many changes...but no fundamental alteration in the power structure."

That isn't to say there wasn't dissent at all. But as Main says, the majority typically outnumbered the minority more than 2-to-1. They were able to maintain this dominance because the majority were willing to champion minority viewpoints every now and then, to successfully keep any kind of unrest among them at bay. Or, as Ketcham writes:

"[To Washington,] The greatest evil of faction and party was not its effect on public policy (though that was bad enough), but rather its narrowing and degradation of political motives, long regarded as the essence of corruption. Parties riveted public attention on partialities and self-interest, and the effect was nothing less than enslavement of the nation to sin and vice. Liberty, for Washington...was not doing what one pleased, if that meant satisfying selfish (factional) interests; rather, it was a positive act of rising above such enthrallment to understand and seek the public good."

In other words, the representatives of the people in government should be able to debate, hear each other out, and even if an idea hurt them personally or went against their own principles, they should be able to put blind party orthodoxy aside and vote in favor of the public good, whatever that might mean in the given circumstances. Just as the House of Burgesses in Washington's earlier years had done.

However, this is the rosy view of Washington. Critics of Virginia politics would argue there was no dissent because the legislature was never truly representative of the people of Virginia. It's easy to hold back dissent when everyone is of the same class, championing their own interests over those of the other classes.

As Phelps states, and Ketcham concurs, to Washington, the threat of partisanship was not its effect on public political policy. Instead, it was two-fold:

1. Partisanship could lead to sectionalism, that is, geographic splits that would threaten the future of the Union, and

2. Partisanship could lead to what we might call a "cult of personality". Some strong and charismatic leader might champion some ideas, which would gain him some followers in Congress and among the people, and pretty soon, the partisans would follow the leader on any misadventure he may decide to take them on, no matter its effect on the public good.

But when it actually came to policy, argues Phelps, Washington never really saw it as too contradictory against his view of party and factionalism to operate as a partisan advocating for one side over the other:

"Washington was never really nonpartisan in the sense of being neutral on public questions of the day. The characterization of Washington as a kind of referee in the great Hamilton-Jefferson struggle, lacking any strong ideological convictions of his own, simply is not true.

"Washington was a committed federalist at the outset and maintained similar enthusiasm for the Federalist agenda throughout his presidency. As early as the struggle over ratification he exhibited a strong "us-them" mentality. He characterized many antifederalists as "unprincipled" and "malignant." He cheered the election to office of friends of the Constitution and thought it appropriate to encourage any maneuverings that would prevent the election of antifederalists...

"Washington was never impartial as to policy goals. He did not become a Federalist in 1793 when compromise with the Jeffersonians was no longer possible. Granted Alexander Hamilton's persuasive role, Washington did not need the perceptions of Hamilton to guide him into the Federalist camp. He held those sentiments before, during, and after his presidency. Yet he could never understand the criticisms of his Jeffersonian opponents because he could not recognize his own partisanship."

And this brings up the second interpretation of what Washington envisioned when he talked about being "above party", and it's likely what Thomas Jefferson himself would have told you if you asked him. Washington's vision was more that the President should be able to make his policy known, and all his appointees should fall in line. He didn't think anybody, including his Cabinet, and including even Congress, should be criticizing the President for his decisions, because the President should be making them in the public interest, whatever the President interpreted that interest as being. The President made a decision, and the Cabinet should support it both publicly and personally when engaging with the President. Congress should be aware of what the President intended to accomplish, so they should act according to what kinds of bills the President should sign and what he wouldn't.

cont'd...