Four years ago, George Herbert Walker Bush seemed a curious supporting actor to Ronald Reagan. He was the patrician alongside the cowboy-populist, the New Englander with the Californian, scion of the Republican establishment with the renegade outsider, favorite of big business with the folk hero of blue-collar workers.

Today, as the Reagan-Bush team embarks on its second term, the match almost seems made in heaven. Reagan calls Bush history's best vice president. Bush says Reagan's leadership skill has made him feel "very fortunate to watch, to keep my eyes open and my mouth shut and see how all that works."

When the two were pictured in newspapers across the country earlier this month, walking chummily in a White House corridor with Secretary of State George P. Shultz between them, a Bush aide remarked: "Look at them. They look like a couple of bowlegged cowboys."

The transformation was complete.

The question for Bush, 60, in the second term is whether he has gained or lost by tailoring himself so faithfully to Reagan. Critics contend that he has forfeited his independence; supporters say his stature has grown from the identification with Reagan and from what they call Bush's show of grace in embracing a subordinate role.

The question may answer itself as the term advances. Bush is expected to run for president in 1988. He said in a recent interview that he will move to articulate his vision for the American future, possibly separate from that of Reagan, if he decides to run.

But he also is committed to spending the next four years in the same style as the last four -- as a self-effacing servant of the president, conferring on issues great and small but voicing opinions to Reagan alone, supporting the president's decisions.

"I feel totally relaxed with the man," Bush said of Reagan. "I'm going to keep supporting him. It's not going to change in any way . . . . He's very gracious. I don't think there's ever been a vice president in history who's ever been treated with that kind of personal regard from the president."

"In a sense, it is a problem that he has created for himself," said former senator Nicholas Brady (R-N.J.), an investment banker and one of several longtime friends with whom Bush has discussed a 1988 race. "Other people might just get out and run, but because of the way George is, he has said he wants to make sure the president's agenda is the one that is focused on.

"The question is, given that -- how do you position yourself?" Brady said. "That's what several of us are trying to think through with him."

Bush's identification with Reagan, which began when the two teamed up for the 1980 campaign, was cemented in the 1984 campaign, when Bush encountered more scrutiny than in the first term. He was the ticket's lead campaigner, defending Reagan nationwide, a somewhat awkward assignment for Reagan's chief challenger of the 1980 primaries.

Bush campaigned more than 300 days against Reagan in 1979 and 1980 as a conservative-moderate, just as the GOP was moving sharply to the right. He was criticized for offering less vision than resume: two terms in Congress from Texas, Republican National Committee chairman, U.N. ambassador, envoy to the People's Republic of China and CIA director.

The transformation of the one-time Reagan foe into a born-again Reaganite became an issue in 1984. Conservative and liberal columnists, generally respectful of Bush throughout his government career, began to treat him as a caricature. The cartoon strip "Doonesbury" portrayed him as having "put his political manhood into a blind trust."

Bush's vice-presidential challenger, Rep. Geraldine A. Ferraro (D-N.Y.), drew some of her loudest campaign applause when she lampooned his loyalty by saying Democratic presidential nominee Walter F. Mondale told her only to "be myself . . . and thank God he never asked me to be like George Bush."

Visibly agitated, Bush defended himself almost daily late in the campaign, calling it the "most personal and ugly" campaign he had faced. His boyish looks became haggard. He became testy, denouncing reporters as "a pack" for asking about his positions on the Equal Rights Amendment and abortion, changed since he joined Reagan.

Longtime friends said they hardly recognized the Bush who emerged in the campaign as Reagan's self-described "cheerleader," trumpeting such Reaganisms as "America is back" and "We're upbeat" in speech after speech.

In private moments, Bush joked about the cheerleading. One morning, jogging before a campaign appearance, he lost track of how many laps he had run and called out to a Secret Service guard:

"Are we finishing eight?"

"No, we're starting nine," was the answer.

"Look at that," Bush said between breaths as he jogged. "I tell everyone to be upbeat, to see the glass half-full instead of half-empty, and then I say we're finishing eight when we're starting nine."

Bush closely guards details of his relationship with Reagan except to say he has been given more influence than any vice president in history. He and Reagan eat lunch together once a week and talk almost daily, according to White House aides.

Aides widely believe that Reagan's conversations with Bush strongly influenced the president's desire to resume arms-control negotiations with the Soviet Union. Bush characteristically declined to take credit, saying: "I have said all along, all along, that Ronald Reagan wants an arms-reduction agreement."

Bush's most visible foreign-policy involvement came in 1983 when Reagan dispatched him to Europe to rally support for the controversial deployment of U.S. intermediate-range nuclear weapons when Reagan's image on the continent was likened to that of a trigger-happy cowboy. Bush garnered favorable media attention throughout his trip and was credited with a major public-relations achievement abroad.

His role in domestic affairs is less clear. He has headed task forces to curb drug traffic and eliminate "burdensome" regulations on business in the name of economic expansion. Some business leaders hailed the "regulatory reform" campaign, but others complained that it accomplished little, and consumer groups charged that it subordinated public health and safety to profits.

On such high-voltage matters as budget and tax policy, religion in politics and social issues, he has not surfaced except as a spokesman for Reagan. His most visible period in the first term came after the assassination attempt against Reagan, when he won skeptics' praise for taking the helm without stepping beyond the role of respectful subordinate.

Bush said his second-term role will not change, but some of his advisers said they expect Reagan to enhance his stature out of appreciation for Bush's loyalty and also out of necessity. After recent Cabinet and staff reshuffling, Bush is the only one of Reagan's five closest first-term associates and friends who remains in the White House.

"I think he's going to use me in places where I can be helpful to him, but I don't think it will ever be done in regard to: this will be helping George along with his visibility," Bush said of Reagan.

Bush said he does not expect Reagan to endorse him in 1988, "and I wouldn't ask." But his aides said they are banking on ties to Reagan and visibility as vice president to keep him ahead of other likely presidential contenders, including Rep. Jack Kemp (R-N.Y.), Senate Majority Leader Robert J. Dole (R-Kan.) and Dole's retired predecessor, Howard H. Baker Jr. (R-Tenn.).

"The vice presidency is very frustrating because in ways it's powerless," a Republican political consultant said. "But it also is an office that all these guys are lusting after because they see it as an excellent leg up on anyone for the presidency." Despite Bush's bruising experiences during the campaign, most Republican strategists say it helped him, particularly with conservatives, who are the key to the nomination and who had been skeptical of Bush because of his 1980 challenge to Reagan and his eastern patrician roots.

These strategists say Bush will be remembered mainly for his performance in the vice-presidential debate, which most polls showed him winning. The perceived victory provided the ticket a much-needed lift after Mondale's strong performance in the first presidential debate.

Vic Gold, longtime adviser and speechwriter for Bush, said Bush "went through a very unpleasant experience in the ampaign, which really was his first exposure to bad press. But I think it quite frankly had to be gone through. The stakes are much, much higher. I'm just glad it happened in 1984 rather than 1988."

Bush declined in an interview to preview the vision he would articulate for 1988, saying, "That's beyond where I want to be." But he said it will not depart from anything he has said as vice president. He said that he has learned invaluable lessons from observing Reagan and that these have made him a stronger potential leader.

Reagan "keeps his focus on certain fundamentals," Bush said. "He does not get bogged down in a lot of detail. Makes decisions and doesn't worry about them. Goes on. Continues to lead . . . . I have great respect for what I see in terms of how you lead something as massive and complex as this country."

Has the experience changed Bush as a person?

"In terms of my own id, why, I hope there's some change there," he said with a smile. "I'm a little more tranquil. I don't get quite as tense about things. I feel older in my knees and my hips."