WITH THE INEVITABILITY of a two-pack-a-day cough, some politicians -- who know better, or ought to -- are reverting to the old-time process of nibbling at the credibility of the government's antitobacco efforts.

Never mind that Jimmy Carter is a fervent advocate cate of preventive health measures. Presumably well rehearsed on the subject of the surgeon general's recent unqualified condemnation of cigarette smoking, the president fielded a press-conference question concerning federal price supports for tobacco this way: "Yes, I intend to continue to support those federal price supports.I think it is a completely legitimate action for the federal government to point our the dangers of smoking. And I don't have any way to dispute the arguments, one side or the other, derived from the scientific examinations, experiments and from medical analyses. I think it's important that people know the dangers of smoking..." (italics ours).

We pass on to Rep. Richardson Preyer (D-N.C.), whose candidacy for a health subcommittee chairmanship we recently supported over protests that, by inheritance, he is a large stockholder in a major pharmaceutical firm. But we are moved to second thoughts about his candidacy when we find him declaring, in part, "The surgeon general's report continues to base its findings on statistics rather than on solid research" -- as though it is possible to study any public health problem without reliance on statistics.

We are not unmindful of the political clout of the tobacco economy. But the fact of the matter is that it is a declining economy, as evidenced by the heavy diversification of the old-line tobacco firms. From the heart of tobaccoland, the Raleigh, N.C., News and Observer recently assailed efforts "to defend cigarette consumption against an avalanche of hard evidence," and went on to urge that the state prepare for the economic jolts that will accompany further declines in cigarette consumption.

That kind of freash and hopeful thinking ought to be noted, and acted upon, by our health-promoting president and by the aspiring chairman of the House health subcommittee.