Politics & conviction

WASHINGTON is recognizably again in the throes of reorganization. The political parties are matching grips on the leadership bat handle to see who will head their teams in the House and Senate. The Democrats, deep in despond over their party's direction, must pick a new national party chairman. State Democratic leaders have been meeting in the Virgin Islands to mull over one fact: As the sum of its parts - notably labor, minorities, the women's movement - the Democratic Party appears unable to command a voter majority for the White House. By their talk, they appear to have just discovered that ''white middle-income Americans'' hold the balance of ballot power.

A Humpty-Dumpty reassembly job will not be enough. Even if labor's support is deemphasized, which seems in order after the results of early union endorsement of Walter Mondale, or if other adjustments are made, the Democrats will have to confront the lapse in political fervor they have endured for at least two presidential elections.

Ronald Reagan, they should note, first leaped on the political scene by offering the philosophical case for a losing candidate. That was 16 years before he was first elected president, and Barry Goldwater, the Republican candidate that year, received an even worse drubbing in the popular vote than the one just dealt Walter Mondale. Republican professionals see New York Gov. Mario Cuomo as best positioned to follow the Reagan formula. He caught attention the same way Mr. Reagan did, in a compelling convention address that articulated traditional Democratic values. He can lay claim to big-state executive experience; Jimmy Carter and Ronald Reagan, after all, used their non-Washington roots to present themselves as innovators. With new income tax cut proposals for New York, Mr. Cuomo seems to be preparing a case for himself as a populist and an effective fiscal manager.

How things turn out for Cuomo or any of the other Democratic hopefuls for 1988 and beyond must await their actions and the public's judgment. What is crucial is to note the long lead times, the fidelity to basic political purposes and views, that mark the difference in success.

In Washington, the managers of government can benefit from a generally improved public confidence in government, which gives them greater room to maneuver in devising solutions.

This is a time when organization redesigns are floated. The Reagan team will remain much as it is at the top. An effort to promote an ''arms-control czar'' to overcome the impasse between the Departments of State and Defense on arms negotiation appears to be going nowhere. The public is not much interested in such details of organization. If there's to be a US arms czar, it would expect him to be the President. That's what presidents are for: to decide the big ones, and to win the concurrence of Congress and the public on broad policy directions.

The same is true of domestic fiscal policy, which takes on added importance at the outset of a four-year presidential cycle. It's up to the President to decide whether to initial the Office of Management and Budget's prescription for reducing the federal deficit by the end of 1988. So assiduous is the Washington rumor mill that he will no doubt first read of many of his own administration's plans in news accounts. He will also get an earful from Republican Senate leaders who fear loss of Senate control in the 1986 election if the President's party is not then perceived as effectively managing the economy.

With wish possibly leading insight, some commentators are talking again of a more moderate second-term Ronald Reagan, especially on arms and summitry. Others emphasize his recent lengthy quotation, during a Cabinet session, taken from his own 1964 political speech, which defined his conservative principles.

The President himself does not likely know now where he will come out when he must weigh long-held convictions against short-term options.

And for the Democrats, the challenge is to define long-range convictions that can add the requisite creative tension to policymaking that commands public respect.