President Reagan's staff, Cabinet parry and thrust in an attempt to discover the limits to their power and authority

"There is no question the President is in charge," says one Reagan aide close to the White House Cabinet operation. "But in the Cabinet itself . . . things are still shaking out. Roles are still being drawn. The crunch hasn't come."

After nearly two months in office, the President's command structure is still forming. His Cabinet and staff are still probing for the limits of their own authority and power. But so far, observers say, there have been no nasty breaks in the amicable, "collegial" Reagan operation.

Some early test of authority and power seems inevitable to White House observers. It could come over any issue, they say. A potential decision crunch could over the question of Japanese auto import quotas. Cabinet members already have lined up publicly against each other on this issue, which is headed for White House review again this week.

Or it could manifest itself in a veto decision, should the administration take an adamant position in dealing with any congressional ambivalence toward Reagan's economic plan.

For the moment, the inner workings of the White House seem to be perking along, insiders say. Cabinet secretaries say they are "keeping in touch" and the policy discussions are "enjoyably frank."

The stellar performance of budget chief David A. Stockman has helped the Reagan administration's entire effort to date, some Cabinet members say. "They think they're in 10 times better shape than if they did not have Stockman," a Cabinet insider says.

The Cabinet split over auto import curbs has been "blown out of proportion" as a test between free traders (Stockman and Treasury Secretary Donald T. Regan) and more politically pragmatic members (Transportation Secretary Andrew L. (Drew) Lewis and Commerce Secretary Malcomb Bladrige), some Reagan staffers contend.

However, to respected outsiders such as former Federal Reserve chairman Arthur F. Burns, the issue is crucial. Yielding to Detroit's pressures for imports would impair the credibility of Reagan's determination to stick with his program until inflation yields, Mr. Burns says.

The early Cabinet consensus has held up remarkably well, but strains are surfacing as department chiefs appoint me deputies and the case for their "constituents" filters up.

"We're hearing not so much that the consensus is breaking up, but that there is some dispute over the priorities which to emphasize in the public arena," says White House scholar Stephen Wayne.

"The early Reagan team effort required everybody to talk the same language and root for the same captain," Wayne says. "Reagan took on people who had at least an initial consensus on both the budget cuts and tax cuts. As other issues come to the fore, that consensus will surely wane."

One White House insider says the Cabinet and White House staff operations have handled successfully a number of issues that "held the potential for deep division," such as foreign aid and tobacco subsidy cuts.

But the lines of power have yet to be clearly drawn, observers agree. White House chief of staff James Baker senior has played an "honest broker" role well -- that is, avoiding skewing the views he represents to the president for decision. At the same time, he feels he must express his own view as chief White House political adviser to the President.

And Secretary of State Alexander M. Haig Jr. has greatly strengthened his hand for a broader role with the President by accepting longtime Reagan confidante William Clark as his second in command.

"What showed Haig's class was his taking Clark without a whimper," another longtime Reagan supporter says. "Clark was a superb chief of staff for Reagan in California. He made decisions. Already Clark is very impressed with Haig. Haig will make Clark his man and have an ear to the President."

None of the White House threesome closest to the President -- Mr. Baker, counselor Edwin Meese, and special aide Michael Deaver -- has yet been fully tested, observers say. Mr. Meese as head of policy development is criticized for losing sight of issues in his "bottomless suitcase" and for failure to brief the President adequately for hid Canada foray -- a replay of complaints early in the Reagan campaign.

And the influence of Mr. Deaver, who oversees the President's schedule, so far has been hard to detect.

"Deaver doesn't get the credit he deserves," says a one Reagan aide who has worked with the Californian for years. "He's remarkably perceptive politically. And he isn't afraid to tell the President he's wrong."

The Reagan White House decision process has been very "unstructured compared with other administration," says a Washington Republican presidential strategist close to the administration. "Often you can get a clearer picture this early, after a new president is elected, of what the power structure is around him.

"It's been loose, really, so it's hard to tell how things are getting done and who's contributing to what.

"It can be assumed that a critical issue will arise and, whatever it is, you will be able to see how other interests play off agaisnt it. This will likely come before summer.

"So far the Cabinet meetings have been rather collegial and haven't decided a whole lot. when there is controversy, it seems they put it off and talk about it some more.

"What's happening is that Haig and Lewis and the others are asserting their powers. Lewis, for example, with the auto imports matter has taken a risk. In internal politics, if he's not somewhat successful on it then he'll suffer from it. If he pushes basically what he wants through, he'll be very strong.

"That's how he's chosen to meet this situation -- to take something that's got to be decided and stake out a position on it before he's told what to do -- and see if can't ram it through."

The White House power structure still is not really settled, observers agree. "They have a situation now that doesn't resolve anything," one Reaganite says. "That'll clear up one way or another. You can't have a permanent discussion."