When the Reagan administration announced its opposition to a key proposal for emergency aid to the home-building industry, the office of Sen. Richard G. Lugar (R-Ind.) cranked out a retaliatory salvo within the hour.

"We need an antirecession, job-creating supplement to the president's economic program: a few sticks of dynamite to break the logjam of the recession," the press release quoted Lugar as saying. "I think the president will eventually agree with Congress on this point."

The warning sounded, well, almost Democratic. But make no mistake about it, Dick Lugar is a solid, lifelong Republican who grew up listening to the very conservative radio voice of Fulton Lewis Jr. at the dinner table. It was the only program Lugar's father would permit to be on while the family ate.

The senator from Indiana has established, in five years, a reputation as one of the Senate's brightest, sharpest members. He knows what's bothering folks back home.

He is one of the 30 senators running for reelection this year, and as such is acutely aware of which party is likely to be blamed if things don't improve before election day.

"The facts of life are, ladies and gentlemen, that we now are the party that's responsible," Lugar told Johnson County Republicans at an annual banquet in Franklin, Ind., this month.

"We can't, at this Lincoln Day, point to the Democrats with alarm and say, 'Those folks have done this to us, kick the rascals out and if we were there, something else would happen,' " he said. "Ronald Reagan is our president. Republicans are in charge of the Senate."

The remarkable thing about such straight talk is that Lugar himself is widely regarded as almost recession-proof. He has handled himself so smoothly in the Senate that even some of his natural enemies, such as politicos from organized labor, tend to think of him as a rather nice guy.

"If he were in the big leagues in baseball, in the majors, he'd be called a journeyman shortstop," said one Senate insider. "He does a good job without your even noticing it. He's unspectacularly a good senator."

Senate Majority Leader Howard H. Baker Jr. (R-Tenn.) rates him more highly. In 1978, Baker turned to two rookies, Lugar and Orrin G. Hatch (R-Utah), to organize a GOP filibuster against labor law revisions that organized labor had made its priority.

Lugar became the general of the successful five-week drive, counting the votes, devising strategy, organizing teams of five to six senators each to take up floor duty in rotation, even putting out a daily "bulletin" that set out assignments and summarized the previous day's action, complete with quotations from the debate.

Lugar "clearly emerged from that as a strong, steady, effective person," said Baker, who frequently calls on Lugar for advice and special assignments.

"He wasn't loud or persistent, but as tempers flared, as they do in the caucuses and private meetings, he was always a steady force," Baker said. "He can polish a position better than anyone I've ever seen. And by that, I mean, he can make it so logical, so attractive, that everyone feels drawn to it."

A valedictorian of both his high school and college classes, and a Rhodes scholar, Lugar appears to have an almost beguiling capacity to listen to the other side.

"He's a very charming guy," said Jim Booe, who is overseeing AFL-CIO political strategy for Senate races this year. "He seems to agree with you a lot, but his voting record" by the AFL-CIO's index of important issues "is worse than Jesse Helms'. His lifetime AFL-CIO voting record, since he got to the Senate in 1977, is only 6 percent. In two of those years, 1979 and 1981, of all the votes we used for recording the index, he didn't vote with us once.

"Usually you have a better perception of who your friends are," he said. "Nobody here considered Lugar that negative, until we looked at the record."

One reason for the senator's political success, according to his mother, Bertha Caldwell, is that he never lets himself get boxed in.

"You walk around a problem. Dick has always done that," she said. "Look at it from every direction. Never get stuck. If one door closes, go through another one."

Another reason, according to aides and colleagues, is that Lugar believes in making things work or, as one fellow senator put it, "He never lets ideology get in the way of pragmatism."

In any case, he worked out the compromises that led to the federal rescue of New York City in 1978 and the Chrysler bailout in 1980--accomplishments that Lugar counts as his biggest Senate achievements.

In the New York case, he insisted on strict fiscal guidelines in return for federal loan guarantees. To prevent Chrysler from going under, he offered amendments that demanded sacrifices by both the United Auto Workers and Chrysler management. Lugar took heat from free-market conservatives on both issues, but he argues that his were the truly conservative positions.

"If we had sent Chrysler into bankruptcy and all the people dependent on it had lost their jobs, that would have caused a very considerable crisis of confidence in our economic system," he said. "Conservatives just don't do that. That goes even more so for New York City. In a federal system, to chuck all that up in the air would be totally irresponsible."

The Chrysler rescue also served more parochial interests. Indiana is second only to Michigan in number of Chrysler employes.

More than 343,000 Hoosiers are out of work. In its cities most dependent on the crippled American automobile industry--Anderson, Kokomo, Newcastle and Muncie--the jobless rate ranges from 17 to 20.2 percent, seasonally adjusted, and it has been at those levels month in and month out longer than most folks care to remember.

None of this deters Lugar from preaching the old-fashioned Republican principles of less government, less taxes and less spending. But unlike the White House, Lugar knows it is not enough to look at the economy and simply "say the cycle will come to an end and someday we'll come out of it."

Thus it was that Lugar could be heard repeating himself around Indiana during the Easter recess about the need for Republicans to show "a great deal more compassion" to the poor, to minorities and to the unemployed, and to embark on an economic recovery plan, with the president's support if possible, without it if necessary.

Lugar advocates "riding herd on defense spending as well as domestic spending" and "offering a very strong hand to organized labor in this state." He also questions President Reagan's assertion that the Soviet Union has nuclear superiority over the United States, and calls for strengthening the Voting Rights Act with the so-called "results test" for determining discrimination, despite the administration's opposition.

Nevertheless, Lugar has voted with Reagan 89 percent of the time, second only to Strom Thurmond (R-S.C.) among senators. If he can get something done in the months ahead, Lugar suggested, it will be because his support for Reagan has earned him "some credit and trust at the White House."

This is unusual for a freshman to claim, but it is not, by all accounts, overstated.

For instance, according to reliable sources, Lugar's $1 billion-a-year housing stimulus bill is a key part of the economic recovery package that Baker and other senior Senate Republicans have been urging on the White House.

But it was stalled in the Senate Banking Committee until deft concessions by Lugar won over two wavering Republicans without compromising his determination to keep it "a jobs bill" that could put 700,000 people in the home-building industry back to work.

The committee approved the measure 15 to 0, after rejecting Democratic amendments to sweeten the pot for realtors and other interests.

"No one expected Lugar to pull this off," one of his aides said. "It was a real coup. So far, it's the only jobs bill that's moving anywhere this year."

Lugar's stand on civil rights is also regarded as highly significant.

His cosponsorship of a strengthened Voting Rights Act "was extremely important to us," said Ralph Neas, executive director of the Leadership Conference on Civil Rights.

Attorney General William French Smith "has been lobbying personally and through emisssaries since January in an effort to get Republicans off the list of cosponsors," Neas said. "But in February Lugar announced he had studied all the documents and the judicial history, and decided to endorse it. I think he's probably one of the most respected senators because of his intelligence and his willingness to do the homework."

Aides say Lugar reads all the time--on the road, in the office--ripping and tearing articles from magazines and newpspapers and making notations for his staff.

"We always called him the E. F. Hutton of the Senate," Lou Gerig, his former press secretary, said. "He isn't a headline grabber. But when he says something, people listen."

A former two-term mayor of Indianapolis, Lugar is so clean-cut he almost squeaks. He refuses to take either the $50- or $75-a-day tax deduction established for federal lawmakers last year, and every year he returns thousands of dollars to the federal treasury from his Senate office expense accounts. He has sent back $886,000 of unspent money, or about 22 percent of his allotments, over the past five years.

And in February he stopped using the congressional frank to send out free mass mailings. Lugar announced that he would send no more until after the November elections.

The same frugality applies to his Senate operation.

"The mark of a good senator is a good staff," said an aide to a top Senate Republican. Lugar has one, and it is trim. He has no speechwriters, since he does best in off-the-cuff speeches.

He also has few highly paid legislative assistants, since he does much of his own homework. He saves on staff by sharing office personnel in Indiana with Sen. Dan Quayle, a Republican.

What staff Lugar has, has authority. The statement concerning the housing bill was drawn up by press secretary Mark Helmke and run past administrative assistant Mitch Daniels. They didn't bother to show it to Lugar before releasing it. They knew his views.

Lugar's most likely opponent this fall is Rep. Floyd Fithian (D-Ind.), who would have his work cut out for him.

Lugar's campaign organization mustered enough volunteers in recent months to copy the voting lists in courthouses throughout the state and come up with the first compilation of every household in Indiana with a registered voter. He has a campaign coordinator in each of the state's 92 counties and an organization that he says will ensure that every Indiana precinct is attended to on Election Day even if the county GOP organization has fallen apart.

One friend, Sen. Alan K. Simpson (R-Wyo.), credits Lugar with the best piece of advice he's received in the Senate.

"One day," Simpson recounted, "I said to him, 'This is madness. The only time you get to think around here is between 10 at night and 2 in the morning.' Old Lugar said he knew of a way. He said, 'Lock your door for an hour a day, you pick the hour. But your staff won't like it.' "

Simpson locks the door as regularly as he can. "You can hear the staff scratching at it like dogs," he chortled. "It gives me a feeling of raw power."

"Old Lugar" turned 50 this month and is a physical-fitness buff with a credible claim of being in better shape than former Dallas Cowboys quarterback Roger Staubach. Lugar runs 15 to 20 miles a week, from 6:30 a.m. runs around the Mall to yearly jaunts in the Carroll County (Ind.) Hog Jog.

Earlier this year, Lugar visited Dr. Kenneth Cooper's aerobics center in Dallas. He took the tests and "max'd out" on the treadmill test, he said.

That involves walking at three miles an hour on a treadmill that increases in elevation by one degree per minute. The first 20 minutes aren't that strenuous, Lugar said, but after that "the going gets rougher," and Cooper, to urge his charges on, names famous people who made it that far.

By 26 minutes, Lugar had about reached the maximum heartbeat for a 50-year-old. Cooper told him, "Roger Staubach made it to 27 minutes, 30 seconds." Lugar got to 27:30 and kept going, ending at 28:21. "I just simply collapsed" in the attendants' arms, he said.

It is unrewarding, however, to try to poke fun at Lugar among the home folks, says Sen. Bob Dole (R-Kan.). Dole tried a bit of warmup humor last year at a Dick Lugar night in Indianapolis and found that "they don't like it."

Lugar is "a straight arrow," Dole says. "You sort of look at him and see the Boy Scout suit on him."

This straight-arrow member of the Senate Banking, Agriculture, Foreign Relations and Intelligence Committees first gained fame as "Richard Nixon's favorite mayor" in the late 1960s. He welcomed the reputation at first, but has been trying to live it down ever since. Then-senator Birch Bayh, a Democrat, used it against him with devastating effect in the Watergate year of 1974.

Lugar overcame the label in his second, successful try, in 1976 against former senator Vance Hartke, another Democrat. and now painstakingly explains, to anyone who asks, how Nixon never called him that. It was a Washington Post reporter who created the tag in a 1970 article, Lugar protests.

Lugar drolly repudiated a suggestion that he could be taken for a liberal for some of the things he's been saying lately.

"No, no," he said, shaking his head with jowl-jiggling vigor. "That would be as bad as 'Nixon's favorite mayor.' No," he said again. "No, no."