SEN. RICHARD LUGAR is not a dispassionate observer of the Republican presidential nominating process. He is the national chairman of Sen. Howard Baker's campaign. Mr. Baker had legitimately planned to convert his prominent role in the Senate debate on SALT II into national attention for his presidential campaign. Unfortunately for Mr. Baker's best-laid plans, the SALT debate in the Senate has been postponed until next year.

Mr. Lugar, as he announced further personnel changes in and an altered electoral strategy for the Baker campaign, mused somewhat wistfully last week: "In the best of all worlds, someone ought to be able to serve in a public office and campaign for president. But that doesn't seem to be the case anymore." (Except, we might amend, in the current case of the incumbent president.)

But Mr. Lugar has hit upon a basic insight about the new way we pick our president. For the first time, being out of office is probably an advantage in winning a presidential nomination. The consensus of the people who constitute a concensus on such matters is that Mr. Baker now trails Ronald Reagan, John Connally and proably George Bush in the Republican field. Mr. Reagan, Mr. Connally and Mr. Bush are all former officeholders and currently full-time candidates. Jimmy Carter was, of course, the soon-to-be-former governor of Georgia when he orginally announced his own candidacy in December 1974.

Traditionally in American presidential campaigns, most decisions have been resource decisions, involving basically the expenditure of a candidate's time or campaign funds. In the past, a late-entering candidate -- like Robert Kennedy in 1968 -- would try to compensate for lost time by spending more freely.

But the traditional formula relating time to money was permanently changed by the Election Reform Act of 1974. Under the law, candidates are limited in the money they can raise from any individual contributor ($1,000), and to what they can spend in any one primary, or overall. At the same time the spending limits were being imposed on candidates, the number of primaries was exploding to the three dozen we will have in 1980. In the process, time has become more important than money to presidential campaigns. Being out of office and able to campaign personally and effectively among small groups in Iowa and New Hampshire gave outsider Jimmy Carter a real lift in 1976. Political strategy is nothing if not imitative. By his frequent trips to and travels in New Hampshire, Mr. Bush has probably already met the residency requirements to register to vote for himself in that state's Feb. 26 primary.

All of this should not come as a shock to either Sen. Lugar or Sen. Baker, who, after all, had intended to be in every living room in Iowa and New Hampshire too -- by courtesy of network evening news about the SALT debate. Mr. Baker's campaign strategy, at least temporarily, has been thwarted by the Iranian mob and its effect on American public opinion and the Senate schedule.