In his first week head-to-head against Ronald Reagan, Walter Mondale has accomplished what a politician desperately hopes to avoid: near universal expressions of pity about his performance. Instead of "Fighting Fritz," it has been "Poor Fritz" being dissected aloud among the wise observers of the press and political worlds, including leaders of his own party.

His style, his personality, his delivery, his voice, his inflection, his message, his ancestry, his emotion, his appearance, perhaps even his glands, are inadequate to his task. At least that's how it appears if you believe all the analysis and ubiquitous offers of advice on how he can change his spots and save his campaign.

Even the candidate seems afflicted with a case of that well-known terminal disease that grips losing politicians: handwringitis.

There was something plaintive, if not pathetic, in the reported exchange between Mondale and House Speaker Thomas P. (Tip) O'Neill Jr. last week when the two Democrats met privately on Capitol Hill.

"Tip, I think I'm out there slugging," the Speaker says Mondale told him. "The question is," replies the Speaker, "is the press showing it?"

Of course not, if indeed the slugger really has been slugging.

No doubt about it, Mondale stands in the worst shape at a comparable point in a presidential campaign since -- well, since September 1952, when Dwight D. Eisenhower was dismaying his press and political admirers alike by running "like a dry creek," and since Sept. 17, 1948, when hapless Harry Truman, everyone's nominee for history's certain all-time loser, prepared to set out on a whistle-stop campaign of the country.

Early in that 1948 campaign, Truman noticed a newspaper article that ignited his well-known temper. Elmo Roper, a premier pollster of the day, had decided to discontinue polling because he believed Republican Thomas E. Dewey already had won the election.

This report so enraged Truman that he dashed off a sharp, handwritten letter (which biographer Robert J. Donovan says he didn't mail):

"Candidates make election contests, not pole sic takers or press comments by paid column writers."

Truman was acutely aware, though, as his memoirs show, of the political dangers that result when the idea of a loser takes hold among media and political commentators.

"Although the polls did not bother me personally," he wrote later, "I was aware that some of the Democratic leaders were discouraged by the dismal picture being painted by the forecasters. I saw that the press was giving widespread publicity to the predictions that the voters would repudiate me and my administration in the fall elections, and I learned from experience that false propaganda can mislead even the most intelligent and well-meaning people."

It was this that caused him to launch his celebrated "give 'em hell" campaign across America. He knew the only way "to circumvent the gloom and pessimism being spread" was to go directly and personally to the people in all parts of the country. If that meant "making talks at all hours at stops along the way where crowds could be assembled to hear the facts," so be it. And so it was.

In that campaign Truman adopted a speaking style he had not used before, except on informal occasions. Of the 76 speeches he made on that tour, 71 were "off the cuff."

As he recalled it: "The technique I used at the whistle stops was simple and straightforward. There were no special 'gimmicks' or oratorical devices. I refused to be 'coached.' I simply told the people in my own language that they had better wake up to the fact that it was their fight.

"If they did not get out and help me win this fight, I emphasized, the Republicans would soon be giving the farmers and the workers the little end of the stick again. I spoke bluntly and sincerely and warned the people that if they were fools enough to accept the little end again, they deserved it."

Temperamentally, Mondale is no Truman, and yes, times and political fashions have changed. Trains won't take you to all the places Truman campaigned, and even if they did, jets get you there quicker and allow you to cover far more ground. Besides, in the age of television, it's an open question whether the presumably jaded and contented voters of today would turn out to hear a candidate on a whistle-stop swing.

But differences notwithstanding, there are analogies and useful lessons in the 1948 Truman example.

Truman never accepted the idea of defeat, and he never tried to be anything but what he was. He believed in speaking bluntly. He knew he could not win unless the people understood the stakes, recognized their self-interest and responded by helping him. They would have to elect him. He also had the stamina and the spark to hammer day after day on the record of his opponents.

Truman understood something else: Americans admire spunk, and they take the business of selecting a president who will guide their destinies and those of their children seriously. They still do.

This campaign, no less than Truman's 36 years ago at the same juncture, is not over. Poll soundings and press predictions aside, Reagan remains vulnerable on his record. And for all the sputterings last week, Mondale demonstrated that he can be an effective campaigner and deliver a serious message in ways that will be heard. His church-and-state speech before B'nai B'rith was important, impressive and in the best American political tradition of addressing serious subjects in measured, careful but strong fashion.

Perhaps the "give 'em hell" kind of campaign is passe politically. But reading them the record, day after day, loudly and clearly, surely is not.

As Old Harry said, in words that wear as well in '84 as in '48: "Any good politician with nerve and a program that is right can win in the face of the stiffest opposition."

NOTE: Among the heavy mail received after my recent column about religion and politics, the response of a minister in Oregon is worth noting. He points out a virtual paraphrase of a portion of George Washington's farewell address in Ronald Reagan's prayer breakfast speech in Dallas -- with one compelling difference. The minister writes:

"The difference, the frightening difference, is that where George Washington writes of religious principles, Ronald Reagan's highly visible followers speak of religious practices. There is a vast difference between the two, a difference that is doing a tremendous disservice to legitimate religion and might even be doing a disservice to Ronald Reagan.

" . . . . The American version of institutional Christianity displayed at the Republican convention in Dallas . . . defines 'faith' in terms of conformity to a set of rules because it is so much easier and more popular to believe in practices than it is to think about principles. Principles are abstract. Practices are concrete. And the American public will rush to support the preacher of practices while turning offended faces from the proclaimer of principles. We should not be surprised. The people did the same thing nearly 2,000 years ago."