On the wall just inside the door to Bob Packwood's offices are four photographs that go a long way toward explaining why the 49-year-old senator has found himself in the eye of the biggest storm now raging on Capitol Hill.

They are portraits of four other present or former senators from Oregon: Wayne Morse, Richard Neuberger, Maurine Neuberger and Mark Hatfield. While their respective styles were very different, ranging from the flamboyance of Morse to the quiet, near-asceticism of Hatfield, all were celebrated in their time for a common trait -- a streak of independence that some have dubbed "the Oregon school of rugged individualism."

Now, adherence to that tradition has made Packwood the member of Congress who has been causing the greatest amount of heartburn at the White House. It's an odd spot for a man who belongs to President Reagan's own party, who claims that only four other senators have a better record of supporting Reagan's legislative goals and who heads the Senate Republican Committee charged with the fiercely partisan task of electing as many Republican senators as possible.

Despite these credentials, Packwood got into Reagan's doghouse because of his role as the uncontested, out-front leader of Senate opposition to the administration's proposed $8.5 billion sale of radar surveillance planes and other aircraft equipment to Saudi Arabia.

His determination to defeat the sale of the Airborne Warning and Control System (AWACS) planes has made Packwood the target of intense White House pressures that have changed from cajolery to sputtering denunciations. But, in the face of this hostility, Packwood stubbornly has insisted he's in the fight to the end.

When he is asked to explain why, Packwood refers to the 1978 controversy when the Senate went along with then-President Carter's decision to sell 62 F15 jet fighter-bombers. In addition to the AWACS planes, the currently proposed sale involves additional equipment for the F15s.

"I went back and reread the arguments of the 1978 debate," he said in a recent interview. "I was struck by how we were told again and again at that time that we had to agree to the sale because it would make Saudi Arabia a moderating influence in the Arab world and induce it to help the Middle East peace process.

"When I began to analyze it, I asked myself what had they really done for peace in the time since except to denounce the Camp David accords, break relations with Egypt and finance the Palestine Liberation Organization. They've done everything they could to wreck the peace process.

"We passed the test of U.S.-Saudi relations in 1978, and we've not had in return a Saudi commitment to the peace process. Until we do, I don't want to sell them any more equipment. It's as simple as that."

Within the Senate, Packwood was far from alone in reaching that conclusion. But he was the first off the mark in deciding to do something about it.

"I didn't see anyone else stepping forward and volunteering to make the calls," he said. "When you sit down with four or five senators to discuss action in a vacuum, it usually leads to nothing. Someone has to say, 'I'll be responsible for A through F, you take G through L, and so on.' Only then do you get action."

"So," he recalled, "I started out in a bipartisan way to see what kind of a response I might get, and it quickly started to pick up steam."

With the help of like-minded senators such as Democrats Alan Cranston of California and Henry M. Jackson of Washington, the "steam" evolved into a Packwood-originated resolution to disapprove the sale that, when it was unveiled on Sept. 17, had the signatures of 50 senators. In addition, Packwood confidently asserted at the time, he had good reason to believe that as many as seven others were prepared to vote against the sale.

If the Senate follows the example set last week by the House in voting against the Saudi sale, it will be blocked. That would be a stinging rebuff to Reagan, who has become accustomed to having his way on Capitol Hill, and the administration has counterattacked with an intensive lobbying campaign in an effort to turn the numbers around.

The campaign has pried three of Packwood's cosponsors from their endorsement of his resolution and has brought several previously uncommitted senators into the president's column. Whether the war of attrition being waged by the White House will succeed in the week remaining before the Senate vote is still unclear; and, in the meantime, an unruffled Packwood continues to employ the tactical skills that won him the Senate Republican Committee chairmanship on behalf of the AWACS opponents.

His reputation as a master political strategist goes back to 1968 when, as an obscure, 36-year-old state representative, he wrested his Senate seat from Wayne Morse, a legendary but aging giant among the congressional mavericks of his time.

In the ensuing years, his skill at campaigning has caused Oregon political observers to describe him as apparently unbeatable on his home ground. His Senate colleagues regard him as among that body's most accomplished managers and manipulators of legislation. In fact, his critics tend to charge him with being more interested in the political ploy than the actual content of public policy.

Perhaps the one thing about which his friends and foes agree is that his legislative record makes him a hard man to pigeonhole under any of the usual political labels. In large part, that's because Packwood has continued the independent ways, sometimes bordering on orneriness, associated with predecessors like Morse.

That, the senator says, is what people expect back in Oregon, a state that historian Arthur M. Schlesinger Jr. once described patronizingly as "a pleasant, homogeneous, self-contained state filled with pleasant, homogeneous, self-contained people . . . ."

Despite the surface homogeneity, there are elements in the state's political heritage -- its early pioneering history, the influence of Scandanavian immigrants, the cosmopolitan character of its biggest city, Portland -- that have made individualism a prized commodity. All of these elements appear to be embodied in Packwood, who comes from Portland and who counts among his forebears a Norwegian immigrant grandmother and a great-grandfather who was an early settler and a member of the state's constitutional convention.

In the Senate, that has translated into a legislative record that seems to wander across the entire liberal-conservative spectrum. Packwood himself delights in pointing out that "whenever a conservative or liberal interest group does a scorecard on how often I've voted for or against their interests, I always come out in the middle -- somewhere in the 40 percent to 60 percent range."

Along the way, he has cultivated generally good relations with both labor and big business, with environmentalists and the timber industry and with a long list of other seemingly disparate interest groups. However, as his willingness to go to the mat with the White House over the AWACS sale demonstrates, Packwood can hardly be called someone who seeks the middle ground as means of playing it safe.

Instead, he clearly relishes the limelight, notoriety and challenge of a good fight. Before the AWACS battle, his outspoken advocacy of abortion had put him in the middle of several punishing encounters with "right-to-life" groups.

"Jerry Falwell came out for my opponent in my last campaign," Packwood recalls. "As far back as 1974, when I was running for re-election, people from the anti-abortion forces spit on my wife. I can still see the spittle running off her face. I can never forget that."

The AWACS controversy also has produced some incidents that he isn't likely to forget soon. At one point, the White House leaked assertions that Packwood took a pro-Israel stance because he was afraid of losing Jewish contributors to his Senate campaign committee.

It's a charge that Packwood refuses to discuss publicly, but it's an open secret on Capitol Hill that he regarded it as an attempt to impugn his motives and portray him as an opportunist. Referring to the pressures being generated by the White House, he said:

"I've been here under four presidents -- Nixon, Ford and Carter before Reagan. There were times when I voted against the others on issues that they regarded as very important. At no time did I experience the intensity of feeling that I'm getting out of the White House on this issue."

But, while he obviously doesn't like the way the administration has behaved toward him, Packwood insists that he doesn't regard the situation as a grudge fight to be carried on into the future.

"As far as I'm concerned, when the AWACS vote is over, that will be last month's battle, whichever way it goes," he said. "There will be lots of other battles for the administration to fight, and I expect to support the president on most of them because our views will be in agreement.

"If the administration wants to put me on a permanent black list, that's up to them. If they do, it will show they don't know much about politics."