WASHINGTON GETS its first taste Monday of Diet Coke with Nutra Sweet, a product that Coke hopes will "better satisfy the demands of diet soft drink consumers and draw new consumers to the low-calorie category, fastest growing major segment of the soft-drink market."

In this political town, where polling is as natural as popping the top of a soda can, soft-drink junkies have been looking for trends since aspartame, the NutraSweet's generic name for NutraSweet, was approved for soft drinks July 1. Interested parties were speculating on the new product's chances even before consumers had a chance to vote in the supermarkets.

Thus, the subjects in a blind tasting of Diet Coke with NutraSweet Thursday took to the polling with enthusiasm. This early canvassing, though it had statistical shortcomings, indicates that the new product is easily identified and that its success apparently will depend largely on what consumers think of the new taste.

The small group of tasters gathered by the Food section identified themselves as:

* Diet Coke drinkers. Each of them tasted 1 1/2 ounces of new Diet Coke with NutraSweet and 1 1/2 ounces of the old diet product.

* Coke drinkers. Each of them tasted 1 1/2 ounces of new Diet Coke with NutraSweet and 1 1/2 ounces of regular Coke with sugar.

* Independents (no participants mentioned Republican or Democratic affiliation) who consume soft drinks infrequently. Each of them had the choice of joining either the Diet Coke or Coke caucus.

Out of 23 tasters, 21 were able to identify Diet Coke with NutraSweet. Only two--a Diet Coke drinker and an independent polled with the Coke group--improperly identified the products.

Furthermore, results indicate that Coke may be right when it says that new drinkers will be attracted to the diet soft drink camp--but those drinkers may be Coke drinkers, not those who do not regularly consume soft drinks. Comments on the major issues, sweetness and aftertaste, included:

* Diet Coke drinkers on sweetness: Two concluded it was "very sweet," one added an "almost too sweet" to that, and a fourth said it was "overly sweet." Another said, "tastes much more like real Coke with sugar."

* Coke drinkers on sweetness: One Coke drinker thought the product was "a little sick-sweet." None of the others in this group found the new drink too sweet.

* Independents on sweetness: Six of the seven independents in the Coke group concluded that Diet Coke with NutraSweet was too sweet, while one took the opposite perspective, saying it was "not really sweet." The one independent in the Diet Coke group said it "tastes like a foreign version of Coke; all syrup and no fizz."

* Diet Coke drinkers on aftertaste: Three Diet Coke drinkers detected an aftertastes, although not neccesarily objectionable ones, noting, "tingling aftertaste," "sweet aftertaste," and finally, "minimal aftertaste."

* Coke drinkers on aftertaste: Observations reflect Coke drinkers' preference for Diet Coke with NutraSweet over other low-calorie soft drinks. Comments included "some aftertaste, but far superior to regular Diet Coke," "taste not very good, although better than saccharin-sweetened drinks," "not as bad as Tab, but lingering chemical aftertaste," "less aftertaste than saccharin."

* Independents on aftertaste: Members of the Coke caucus recognized an aftertaste--"first tastes just like Coke, then fades and becomes metallic," "much aftertaste," "tastes like other artificial sweeteners," "strange aftertaste, not unpleasant and dissipates quickly," "even sweeter aftertaste, than initial taste ." One replied "no aftertaste." No comment from the Diet Coke independent.

Washington is the third city, after Birmingham, Ala., and Chicago, to receive new Diet Coke with NutraSweet, which will be replacing the company's original Diet Coke formula with all-saccharin sweetening. It should reach all local stores by Wednesday.

Even New Hampshire has to wait during this campaign, although Diet Coke with NutraSweet will be available nationally by the end of the year in New Hampshire and the rest of the nation by the end of the year, and then Diet Coke sweetened solely by saccharin will be gone from the marketplace. The wholesale price to stores will remain the same, according to a spokesman from the Mid-Atlantic Bottling Co., although aspartame is more expensive to produce than saccharin.

Diet Coke with NutraSweet contains a blend of saccharin and aspartame--saccharin to ensure stability and shelf life and aspartame to offset the "characteristic taste of saccharin," says the company. Coke says only that the product's sweetening contains "less than 50 percent" aspartame. although Industry analysts estimate that the ratio of the sweetening in the new Diet Coke is about 25 percent aspartame to and 75 percent saccharin. The old and new Diet Cokes each contain one calorie per 16-ounce can, less for a 12-ounce serving. Sugar-sweetened Coke is 144 calories per 12-ounce can.

Reformulation of Caffeine-free Diet Coke with NutraSweet will follow in the next few weeks, and a Coke spokesman said the company's other low-calorie soft drinks--Tab and sugar-free Sprite--are "under consideration" for reformulating with the new sweetener. "It may be that consumers tell us they like Tab the way it is," said the spokesman. "There is a very loyal Tab audience." Aspartame, the generic name of the sugar substitute trademarked NutraSweet,The Food and Drug Administration approved aspartame for soft drinks last month.Coke signed a contract with NutraSweet's manufacturer, G.D. Searle & Co., on Aug. 1, and is the first soft-drink company to kick off a NutraSweet product in Washington. Royal Crown Cola Co. has begun distribution of Salt/Sodium Free Diet Rite Cola, which is also caffeine free and contains NutraSweet, in selected Midwestern and Southwestern cities. It will be sold in Washington sometime before Oct. 1, said a company spokesman.

Both Diet Coke and Diet Coke with NutraSweet contain one calorie per 16-ounce can, less for a 12-ounce serving. Sugar-sweetened Coke is 144 calories per 12-ounce can.

Before signing a contract for aspartame, Coke did extensive in-house taste tests, using employes who regulary drink low-calorie sodas, according to a company spokesman. After the contract signing, the company polled outside consumers, asking that they rate Diet Coke with NutraSweet against other cola products. A spokesman from Coke said that the test results indicated that two types of drinkers--those who normally consume diet soft drinks and those who don't--would be attracted to Coke's new product.