To his constituency--the same one that endorsed the presidential candidacies of Richard Nixon, Gerald Ford and Ronald Reagan--he recommended, in the election year of 1966, this answer to the problem of increased federal spending: "Let's do it by tax increase and not by inflation." In 1967, his position on Vietnam was to "say as plainly as I can that I was wrong two years ago, and I firmly believe President Johnson's advisers are wrong today."

Never a weathervane, he saw the leader's job as to lead, something he did on such thorny political issues as civil rights, welfare and campaign finance reform. And over 22 years in the House, Rep. Morris K. Udall has presented his controversial views not quietly to Manhattan salons or other liberal enclaves but publicly to the voters of his district in his congressional newsletters, which are unique for their detail, their fairness and their thoughtfulness.

Most congressional newsletters are none of the above, filled with self-promoting puffery and photos of the legislator welcoming a celebrity or consitutent to the Capitol. The other almost invariable feature is the continuing saga of how "our congressman" is simultaneously cutting unnecessary federal spending and getting deserved federal aid for "our" district. To read such newsletters is to conclude that most congressmen do not much respect the intelligence of their constituents. To read Udall's over two decades is to appreciate the politics of respect that he has practiced.

Now 60 and visibly slowed in step by Parkinson's disease, Udall is publicly deciding whether to run again for president in 1984. He ran before, in 1976, finshing second to Jimmy Carter while leading a campaign more notable for its high spirits and succession of managers than for its competence or direction. That year, the easygoing Udall went much too easy on his campaign staff and allowed himself, surely the most likable of the candidates, to be seen as the embodiment of the 1976 liberal issues floating around the nation. His personality was lost in his position papers.

As to 1984, Udall frankly acknowledges that his family has made a "pretty potent argument" against the race. And Udall has always lacked that all-consuming conviction that he, and he alone, can save the Western world. In 1976, he used to warm up crowds by telling about walking into a New Hampshire barber shop, putting out his hand to the man in the first chair and saying: "Hi, I'm Mo Udall and I'm running for president." To which the man responded: "Yeh, we were just laughing about it."

There are problems beyond the candidate's health. There is the suspicion that some House colleagues are encouraging Udall because he represents a plausible and comfortable hiding place for the time being. The Udall ideas have not been as fresh in the '80s as they were in the '60s and '70s. Like any candidate, Udall must present the compelling rationale for his candidacy.

But whatever he decides about 1984, Udall's newsletters from 1961 on should be required reading for anyone who wants to be president--or county commissioner. He is that most rare of liberals, one who likes both mankind and people.