The body blows to President Reagan's political standing in Washington and other world capitals this past month have not visibly damaged his reputation as a popular and formidable figure in the heartland region around this city.

Despite the batterings of the Bitburg cemetery controversy and setbacks to his economic, defense and diplomatic policy on Capitol Hill and at the Bonn summit, there are few signs of a serious second-term slump among voters of this area -- a mixture of blue-collar workers, farmers, small-businessmen and academics, many of whom broke from their normal Democratic partisanship to help Reagan to victory last November.

From Bill Michalski, proprietor of a corner grocery on the heavily Democratic west side and maker of a locally renowned sausage, to Willard Martin, a worker in a Goshen motor-home factory, to Bill Healy, the newly elected student body president at the University of Notre Dame, the people who supported Reagan last November are still rooting for him.

There are campus protests about Reagan's Nicaragua policy, anger about layoffs among older unionists at Bendix, real concerns among farm families about their cost-price squeeze and a growing rumble that some think could become a roar of complaint about prospective Social Security cutbacks.

But three days of interviews by The Washington Post in the diverse and politically marginal 3rd Congressional District bear out the view of South Bend Mayor Roger Parent, a staunch Democrat and ardent supporter of Walter F. Mondale last year, that although the recent controversies have "made it easier for other politicians to go after him, I think you'll find very substantial support for Ronald Reagan still."

That support is based on the belief that, despite an unemployment rate here above the national average, Reagan has the country on the right track economically; that he is a strong leader with real convictions; and that the Democrats -- still shadowed by the unpopularity of Mondale and Jimmy Carter -- offer only an example of congressional obstructionism on such issues as the budget deficit.

There are growing worries among some of Reagan's staunchest supporters in this area that the recent controversies and setbacks have cost him momentum and endangered some of the objectives of his second term -- especially a major whack at that deficit.

Many of them hope Reagan will see the budget fight through to the end when he gets back to Washington today, but others fear that the public is bored with the subject and indifferent to any cuts except those affecting them directly.

But it's clear that in this area, at least, where there are only 900 Jewish families, the visit to the Bitburg cemetery where Nazis are buried poses much less of a threat to Reagan's and the Republicans' political future than does a possible downturn in the economy. "There's no groundswell against him" on Bitburg, said Lewis S. Haber, associate editor of the South Bend Tribune, who wrote the paper's editorial criticizing the visit.

"The firestorm is over, and he came out okay," agreed John Roos, a Notre Dame political scientist who has served as the top strategist for recent Democratic congressional campaigns here. At Penn High School, serving a rapidly growing area 15 miles east of here, two classes of 12th-grade government students agreed overwhelmingly that Reagan's trip was right and that the controversy was mainly a result of "media hype."

The 3rd District is not all of America, of course, but it does provide a cross-section of opinion in an area where Reagan's fortunes and policies are weighed closely in the balance. Rep. John Patrick Hiler (R-Ind.), a 32-year-old conservative, beat veteran Rep. John Brademas (D-Ind.) in 1980, thanks to Reagan's coattails. He barely held the seat in the recession year 1982, and gained an 11,000-vote victory last November over a Democratic prosecutor who ran 13,000 votes ahead of Mondale.

In recent weeks, the congressman said, he has heard and felt criticism of Reagan's policies on Nicaragua -- his South Bend office was picketed three times -- on farm credit and on proposed budget cuts for Social Security, Medicare and Amtrak.

But Hiler has stuck with Reagan on these issues, and doesn't think he will suffer politically for doing so. "The mail is not vitriolic," he said, "and the town meetings are almost dull. Even the people who disagree with particular aspects of his policy don't feel the world has fallen apart. They like Ronald Reagan and his leadership abilities, and they feel the country has turned around."

Interviews here confirm almost every point of that analysis. It may not be surprising that Thomas L. Dusthimer, chairman of the First National Bank in Elkhart, a Republican stronghold, says, in a flurry of mixed metaphors, "The glow may not be as great surrounding Reagan , but I don't think there's any star in the wings in either party that's stealing his thunder."

But one hears almost the same thing from Lester J. Fox, 60, a lifelong Democrat, an officer of the United Auto Workers local at Studebaker when South Bend's biggest employer shut its doors in 1963 and a former antipoverty worker, who runs the city's social services programs for the elderly.

"Whoever described Reagan as a Teflon president was accurate," he said. "He still would rate very high among the general population here, including the elderly, notwithstanding his proposed cap on COLAs cost-of-living adjustments . He still has that ability to communicate, even to people who are losing in the process."

The Social Security issue remains touchy for Reagan, however. It has cost him the support of George C. Biddlecome, 75, a Republican and retired superintendent of mails in Elkhart. Declaring himself "disillusioned" with Reagan's failure to "keep his word" on Social Security, Biddlecome said, "I don't think he's representing the people any more. He's just representing big people."

But most of Reagan's vehement critics are concentrated among the diehard, mostly elderly, Democrats, the blacks, who form 18 percent of the local population, and -- since Bitburg -- the Jews.

Joe Burkas, the ex-president of the UAW local at Bendix, said, "We've got 3,500 retirees in our local, and they're scared to death about Social Security. They know what Reagan said in the campaign, and they know what he's saying now. They're not dumb."

Roland W. Chamblee, a black physician and former head of the city's Black American Coalition, said, "I'm really hoping Reagan fails, because his philosophy is so damned different than the things I'm accustomed to feeling."

Angela Hooten, a Tuskegee, Ala., black who was voted the outstanding student in this spring's senior class at Notre Dame, admonished a fellow student who praised Reagan for "getting us back to a normal America, where you could go to college, get a good job, marry, settle down and have a good life, like they did in the '50s."

"Everything wasn't peachy-keen for my people in the '50s," she said. "I can't contemplate going back to the '50s and facing discrimination at that level. That's why we have a real question about Reagan's commitment to civil rights."

Dorothy Jaffee, a longtime volunteer activist in community and Democratic Party affairs, said that even though many members of the Jewish community appreciate Reagan's support of Israel and agree with his economic policies, they "will not ever forgive him for Bitburg , no matter what he does. It hurts too deep."

Jaffee said, "The outrage is not just among Jews. It's everybody, including veterans and some of the staunchest Republicans." But interviews with other opinion leaders and voters suggested something quite different.

Bob Beutter, the Republican mayor of Mishawaka, South Bend's neighbor city, said, "I didn't sense any great talk in the streets about Bitburg. People are more concerned about whether their streets are paved than where is the president visiting."

Reg Wagle, manager of a Mishawaka TV store, said "it makes my skin crawl" when he thinks about the Holocaust.

"We're not happy that our president went to Bitburg," he said, "but if he felt that that was an important step for our relations with the community of Europe, then that's why we elected him. He's our leader, and if he thought that was the right thing to do, then I'll support him."

The Rev. Gene Kazmierczak, pastor of St. Adelbert's Roman Catholic church on the west side here, said he thought Reagan's visit to Bitburg "exemplifies Christianity in the finest sense. Our cemeteries are full of sinners, but they don't contaminate others. Why all the fuss here? It's a nationality thing. I hate to bring in the Hebrews. They're very good friends, but they made the cemetery visit a racial issue . . . . And he stood up to it. I give Reagan credit."

Underlying almost all the comments was a focus on economic issues -- not surprising in a city that has lost jobs and population in the past two decades, but sees itself struggling toward a brighter future.

Bank President Christopher J. Murphy III and lawyer Daniel A. Manion, both Reagan boosters, want him to bear down on the deficit issue, which they regard as the main threat to the economy.

But most of those interviewed are optimistic about their futures and supportive of Reagan's policies. As in the last campaign, the support gets stronger in lower age groups.

Bill Michalski, 43, the sausage-maker, has a father-in-law who works at Bendix who he says "I can't even talk to about Reagan, because he thinks he's out to bust the unions." But Michalski doesn't "believe in giving everything to everybody, the way the Democrats were doing," and says, " budget director David Stockman impresses the hell out of me. He's trying to run the government the way I run my store."

Healy, the Notre Dame student president, said, "I may lose my guaranteed student loan, but I've got a lot better future to look forward to than I would if the Democrats were back in there."

And at Penn High, two classes of seniors were equally laudatory about Reagan. In a scene that looked almost like a shot from a 1984 Republican TV ad, heads nodded all around the room when student Dean Rupf said, "President Reagan makes you feel like we're on our way back up to the top as a nation."