The twin themes emblazoned on campaign posters across this Alpine country speak of a man who embodies national pride and integrity: "an Austrian the world trusts," and "his experience for us all."

But within the space of a week, the slogans have assumed a haunting irony in this murky capital where, as Graham Greene's classic work "The Third Man" vividly demonstrated, things are never quite the way they seem.

During a diplomatic career spanning four decades and two terms as United Nations secretary general, Kurt Waldheim epitomized the urbane and cautious civil servant who made friends and allies by skirting any hint of controversy.

But now, as the conservative candidate for the presidency of Austria, he has seen his promotional image as honorable native son challenged for allegedly concealing a Nazi background and wartime military service in a German command accused of committing atrocities and deporting more than 40,000 Greek Jews.

The charges, published last week in the independent Austrian magazine Profil and The New York Times, reportedly stemmed from a four-week investigation of Waldheim's past in German and Austrian archives by representatives of the World Jewish Congress.

In most political campaigns, the emergence of such documented accusations might be considered a shattering blow to chances for high office. But for Waldheim, such allegations have generated a wave of sympathy -- and a surge in political support -- from fellow citizens who do not like to be reminded of the dark era when many of them applauded the incorporation of their country into Nazi Germany.

Elan Steinberg, executive director of the World Jewish Congress in New York, said in a telephone interview that congress representatives came across the evidence while researching Nazi war crimes. He said their research yielded documentary proof that Waldheim, then 20 years old, joined the Nazi student federation on April 1, 1938, and the following November entered the Sturm Abteilung, or SA, a Nazi paramilitary outfit known as the brown shirts.

In contrast to his autobiography, which mentions only that Waldheim spent the years 1942 and 1943 in Vienna as a law student, Steinberg said the congress also discovered that Waldheim served on the staff of Gen. Alexander Loehr, a German commander whose troops waged brutal campaigns against Yugoslav partisans and engaged in mass deportation of Greek Jews. Loehr was executed in 1947 by Yugoslavia for war crimes.

"We are saying that Waldheim is a Nazi, a liar, and that for more than 40 years he has deceived people about his military record," Steinberg said in a telephone interview. Noting that the Austrian government is now promoting a project to teach the country's youth the truth about the Nazi past, Steinberg said it would be a "sad lesson" if Waldheim is elected president in the May 4 vote.

In an interview here, Waldheim -- who has denounced the charges as "grotesque" and insisted they are part of a campaign to sabotage his election prospects -- did not refute the veracity of the documents or photographs involved. He stressed instead that the material and the reports based upon them conveyed a gross distortion of the nature of his background during the war.

Waldheim's Socialist opponent, Kurt Steyrer, firmly denied that his party was involved in smear tactics and has pledged not to focus on Waldheim's wartime record as a campaign issue.

Even though he has been vague about key aspects of the wartime period, Waldheim appears to be turning the charges to political advantage. Some opinion polls show that since the controversy erupted, Waldheim's lead over Steyrer has doubled, rising to 42 percent of the projected vote against 34 percent for the Socialist.

In public speeches and on television Waldheim has depicted himself as the victim of a conspiracy by political enemies at home and revenge-minded people abroad.

"This defamation campaign is being raised only now because I have a chance to win the election," Waldheim said in the interview, conducted in his spacious law office. "It comes from two directions: it seeks to create the impression I was a Nazi and to undermine my international prestige."

Waldheim said his name was mysteriously appended, without his direct knowledge, to membership lists in the Nazi student organization and the brown shirts. He noted that the student card did not bear his signature, and he contended that his name and those of other members of a Vienna riding club to which he belonged were probably absorbed into the SA mounted regiments after Austria was annexed by Nazi Germany.

Concerning his service in the Balkans under Loehr, Waldheim said he worked simply as an interpreter and ordnance officer because of an earlier war wound. He said he performed only minor tasks and encountered Loehr three times during his entire service. Until last week, Waldheim said, he never realized that any atrocities or deportations of Greek Jews from Salonika were carried out by colleagues in his unit.

"I never had anything to do with such cruelties," Waldheim said, as he fidgeted with his tie. "I was in the hills, doing my work, rarely going to Salonika, so I never knew."

Simon Wiesenthal, the famed Nazi hunter based in Vienna, said in an interview here that he was inclined to believe Waldheim's statement that he never belonged to any Nazi organization and that he never became involved in the actual deportation of Jews.

But Wiesenthal said he cannot accept Waldheim's claims that he remained oblivious to the fact that more than 2,000 Jews a day were being transported out of Salonika under orders that originated with Adolf Eichmann in Berlin.

"The SS asked and got trains and food from the German Army in the Balkans to take out more than 40,000 people to Auschwitz," Wiesenthal said. "It went on for many months, and I cannot believe that Waldheim did not know what was going on."

Wiesenthal said he was not surprised by the outrage and exasperation expressed by many Austrians in support of Waldheim in recent days. He said that the smooth transition to Nazi rule in the 1938 annexation, as engineered by Austrian-born Adolf Hitler, led to the rapid absorption of many social and sporting clubs under the Nazi aegis.

"In this way maybe 20 percent of all Austrians were linked to some kind of Nazi organization," Wiesenthal said.

"People here do not like to recall this part of their history."

He said he expected that Waldheim would reap political benefits from public dismay with renewed attention on the wartime past and he predicted that Waldheim would win the presidential election, unless some new revelation offers a damning contradiction of Waldheim's account of his past.