In the 1980 campaign, candidate Ronald Reagan mocked the twists and turns in President Carter's efforts to stimulate the economy while holding down inflation.

"He's just announced his fifth economic program in three years," Reagan liked to say, suggesting his rival lacked both competency and a clear sense of direction.

Now Reagan, too, appears to have arrived at a point of policy adjustment. On the one hand, after promising before the election not to support a tax increase next year, he this week endorsed a 5-cent-a-gallon increase in the federal gasoline tax, to pay for what he calls a highway program and members of Congress call a jobs program. At the same time, he is considering here this weekend whether to propose acceleration of the final stages of the three-year income tax cut he pushed through Congress in 1981.

On one level, Reagan seems to be making contradictory proposals and shifting ground -- not staying the course but moving to stimulate the economy; seeking to do so through both a tax increase and a tax cut and creating a new public works program perilously like those he has so often criticized in the past. But on a more fundamental level his advisers say this is not so, that he has indeed found it both personally appealing and politically wise to make some adjustments in his program, but that these are tactical only. His basic principles remain the same, in this view.

Reagan endorsed the gasoline tax increase only after congressional leaders made it clear they would push the proposal through the lame-duck session with or without him. Even though he had promised not to raise taxes and doubted whether the program would on balance do much to alleviate the nation's 10.4 percent unemployment rate, the president is said here to have decided he had little to lose by supporting the highway tax and repair program.

As the former governor of a state where freeways are king, Reagan apparently needed little convincing that the transportation problem was severe and important despite his general philosophy that the federal government should do less. "The argument can be made that the roads and bridges are a special federal responsibility and that they are in bad shape," said one of the president's economic advisers, who requested anonymity.

Moreover, this insider added, embracing the gas tax was sensible politically because "you've got a big train coming at you in the form of jobs programs. You're going to have one, never mind that it doesn't make sense. So you go for a little gas tax. You knock the props out from under a bad jobs program."

The idea of asking Congress to advance the tax cut from July to January carries a similar reasoning.

On the surface, it would seem to make little sense because of opposition from both Republicans and Democrats on Capitol Hill, concerned about the growing size of the budget deficit.

But White House officials are known to be worried that Democrats might attempt to eliminate or modify the third installment of the Reagan tax cut.

"If I were in his position, I would want to speed up the 10 percent cut--and that way not lose it altogether when it's supposed to come in," said the Reagan adviser, who worked on the tax cut plan in the campaign and later in the White House.

In this view, which other administration officials share, Reagan is not so much moving toward stimulus as going on the offensive to protect stimulus already in place -- the third and in his view all-important year of the tax cut.

"Whether or not you speed it up six months, I think most people who are counting on it would not accuse you of inconsistency," the adviser said. "They would accuse you of over-consistency."

By that, he explained, a Reagan proposal to accelerate the third installment would be a tactical sign that the president was determined not to give ground on the issue. "If he comes out for a speed-up, it really confirms the basic thrust" of Reagan's intentions, he added.

No matter what Reagan finally decides to do about speeding up the tax cut, the administration debate on the issue has once again focused attention on the difficult fiscal trade-offs that Reagan didn't anticipate in 1980.

During the campaign, Reagan talked optimistically about balancing the budget, increasing military spending, and cutting taxes. He sidestepped the seeming impossibility of doing all three in a stagnating economy, saying simply that it could be accomplished through greater future economic growth and elimination of fraud, waste and abuse in government. He made highly optimistic predictions about the economy's future performance.

Now, he is confronted with choices among the intensely conflicting priorities he set, and there are some who believe that advancing the tax cut is another signal that deficits will be the weak point among them, as they were in 1981 and 1982.

They note that accelerating the tax cut would add $15 billion to the deficit, and this is one of the strongest arguments being made within the administration against acceleration. By making a decision over the Thanksgiving holiday in the relative solitude of his ranch, Reagan may be signaling in a larger sense the direction his administration will take.

"People's fears about the deficits are fueled by the absolute numbers," said the economic adviser, who is among those who believe Reagan will ultimately have to live with massive deficits for the rest of his presidency if he insists on keeping his other promises. "What's significant is the size of the deficit when compared with the size of the overall economy. It's gotten large, but not way out of hand."

The president, of course, has not made that argument personally, and insists he still intends to trim spending even if his original promise to balance the budget by fiscal year 1984 has long been thrown by the wayside.