With winter's snows at last reduced to spring mud, Moscow slogs toward its Summer Olympic Games sustained by dogged hopes of eventual victory in showcasing the Communist system to the world.

Thousands of workers in padded khaki jackets groom and color the capital's public face, landscaping the raw new sports sites and gliding and painting the city's ancient monuments for the tourist hordes to come.

Meanwhile, officials of the powerful state-run Olympic directorate cautiously confront a future made dismal by the American boycott of the Games and probable cancellation of comprehensive North American television coverage by NBC.

The official stance is poised between outright bitterness and stiff-upper-lip wounded pride.

The official line continues to blame the president for "political blackmail," but that has been modified recently.

Vsevolod Sovva, information chief at the new Olympic press center in central Moscow, confided his critical remarks in a recent interview to this homeric aphorism: "Jupiter, you are angry and that means you aren't right." He added that "Eric Heiden spoke his mind after the White House meeting, and he's a very competent sportsman."

The Soviets have widely publicized Heiden's support of American participation, after first hailing the Olympic skater's achievements at the Winter Games in Lake Placid. Sovva said he believed the U.S. successes at the February Games, which included a gold medal for the U.S. hockey team, may have "taken some of the tension" out of the confrontation over the Summer Games.

Sovva expressed confidence that the commercial ban by the White House, which apparently takes in such firms as Kodak (which was to develop newsfilm at the press center) may be bypassed by the Soviets doing these tasks themselves, or by last-minute deals with non-American foreign firms.

But the big question mark is whether NBC will broadcast the Games. If the U.S. does not participate, network officials have said, neither will NBC. The White House ban on further equipment shipments to Moscow by NBC apparently has stalled completion of the network's television center.

The Carter action also suspended NBC payments to the Soviets under terms of the $100 million deal for TV coverage. Some Westerners had speculated that the interruption might bring a Soviet retaliation. But Sovva declared, "This is a technical question that can be worked out. The whole program for establishing the technical base for full coverage by NBC will proceed."

And if the network finally is barred from covering the Games, Sovva said, "Then we have many others who will carry the news," and named the CBC, and with a straight face, the Voice of America. Meanwhile, accreditation of American reporters, along with all other foreign newsmen, are planned to proceed regardless of the White House boycott decision.

The Soviets say that virtually all projects from sports complexes to the Olympic Village, telecommunications to bus schedules, menus to souvenirs, are nearing completion. About 20,000 American visitors were expected, among the several hundred thousand foreign tourists, but the number obviously has dropped, though it is unclear from here by how much.

Soviet confidence in their nuts-and-bolts performance remains high. The party newspaper Pravda last weekend interviewed the city's tourism chairman, R.V. Chistyakov, who characteristically maintained he feels "no pre-Olympic fever." He offered the customary Soviet litany of statistical accomplishments to show that Moscow is ready to freight, feed, and entertain the foreigners.

Recently the Soviets noted with aggressive pride that about 90 percent of all foreign tourist Olympic tickets have been sold, "considerably surpassing comparable figures" for the Munich and Montreal Games. The Tass press agency said the national allotments for 10 countries' tourists, including potential boycotters Britain and West Germany, are sold out, and that additional tickets have been provided Britain and eight other countries requesting them. It added that foreign sports fans will receive their tickets May 15.

But beneath the enthusiastic official face, the authorities' nervousness over possible ideological contamination from the foreigners seems to be intensifying. Some party cadres are said by Soviet sources to be undergoing special propaganda training to sharpen their skills at parrying foreign influences. And many parents continue to report that schoolteachers are warning their students against contacts with foreign students for fear of being contaminated by specially prepared, infected chewing gum and other threats.