Republican Party affiliation has declined to its lowest point in Gallup surveys conducted over the last four decades.

The most recent audit, based on interviews with more than 9,000 persons, shows only one person in five (20 per cent) classifying himself or herself as a Republican.

While GOP affiliation is at its lowest point to date, having declined eight percentage points since the fall of 1972, Democratic Party affiliation is near its high point. The current Democratic figure of 49 per cent is the higest since the spring of 1965 and only four points under the all-time high of 53 per cent recorded in early 1964.

The propotion of independents - about three in 10. or 31 per cent - has remained roughly at the same level during recent years.

The decline of GOP affiliation has been across the - board in terms of population groups. It has occurred about equally among men and women and among the various educational levels. The GOP fall-off has been less pronounced among nonwhites than whites, but the propotion of nowwhites who calssified themselves as Republicans was already relatively small.

Alkthough regional differences are not sharp, GOP allegiance has slipped somwhat more in the far West is elsewhere. The decline of the GOP in the West is particularly interesting because this was where President Carter fared least well in last fall's election.

The highest proportion of Republicans is found among farmers and those in professional and business occupation groups, where one-third classify themselves as Republicans.