Ronald Reagan is giving Americans a presidency consistent in acts, and even adjectives, with the one that he talked about during the last election campaign--and for that matter during most of the last two decades.

Last week the president found himself confronted with two crucial questions of compromise as he prepared his latest economic speech to the nation. His options already were reduced by his own resolve to move toward a balanced budget by 1984 without making significant cuts in defense spending. Now, each compromise had advocates in high places.

The first was forced on him semi-publicly: Republican elders in Congress warned that his plan to delay Social Security's cost-of-living increases by three months could jeopardize enactment of his entire new round of budget cuts. Reagan reluctantly yielded.

The second was debated privately in a meeting in the Oval Office: a late option pressed most strongly by Office of Management and Budget Director David A. Stockman to delay implementing the recently hard-won tax cuts by three months to lessen the depth of cuts needed in other domestic programs. On this Reagan would not be moved.

"I just can't do that," the president said, according to a senior adviser who was in the meeting. "I'm just not going to retreat from our fundamental goals." The president said even an appearance of retreat now could undermine the confidence of the public and the marketplace in his economic program.

The decisions of recent days have charted not only the course Reagan intends to take in the years to come but also the bounds beyond which he will not sail as he tacks politically in very narrow channels. One of his senior advisers views this past week as the most telling of the Reagan presidency because "he showed that he has the ability to distinguish between fundamental goals of his presidency and his lesser priorities. He showed himself able to move on his secondary goals in order to achieve his primary ones."

So it is that Reagan has resolved to give America a presidency consistent with his decades of rhetoric on balancing the budget, strengthening defense, and cutting taxes. It will not, it turns out, be a presidency consistent with his own pledge of Feb. 18. He promised then that "those who, through no fault of their own, must depend on the rest of us--the poverty-stricken, the disabled, the elderly, all those with true need--can rest assured that the social safety net of programs they depend on are exempt from any cuts."

He went on: "The full retirement benefits of the more than 34 million Social Security recipients will be continued, along with an annual cost-of-living increase. Medicare will not be cut, nor will supplemental income for the blind, the aged, and the disabled. And funding will continue for veterans' pensions. School breakfasts and lunches for the children of low-income families will continue, as will nutrition and other special services for the aging."

Reagan officials have sought to embellish that pledge into obscurity ever since. They have lapsed into vagueness about how the "social safety net" is really of undefined dimensions, assuring only that it will be large enough to save the "truly needy," also undefined. Enter Stockman, who conceded last week that the social safety net "is a term of art, the content of which is applied to each case as it comes along . . . ."

But much is known: All of the entitlement programs, including those aiding the blind, the aged and the disabled--all of them except Social Security--are now being looked at for cuts that will total $2.6 billion in 1982 outlays, $10 billion in 1983 and $15 billion in 1984. By the administration's own list, the programs under review include Medicare, Medicaid, food stamps, subsidized housing, aid to families with dependent children, railroad retirement pensions, black lung, federal civilian employe and military retirement, and student loans.

In restful Camp David, Reagan sat down to do a little preliminary speech drafting.

There was something he had been wanting to get off his chest ever since his springtime package of Social Security "reforms" had been slapped down 96 to 0 by the Senate. In fact, he had been wanting to say it for years, because he had been buffeted time after time by charges that he was out to undo the Social Security benefits of America's retirees.

"I'd like to turn to another subject which I know has many of you very concerned and even frightened . . . I feel I must clear the air. There has been a great deal of misinformation and for that matter pure demagoguery on the subject of Social Security . . . ."

When he first sat down to focus on his latest economic recovery speech, he wrote not about taxes and not about the budget, but about injustices done to his views on Social Security. At the time, he thought the one-time-only delay in the cost-of-living increase would be part of his economic package.

Stockman had strongly urged that the benefits increase be delayed for three months. White House chief of staff James A. Baker III had disagreed, according to one senior administration source, urging that the entire Social Security matter be delayed until it could be dealt with comprehensively.

By the time the Republican congressional leaders weighed in with similar advice, Reagan agreed--with utmost reluctance--not to press his cost-of-living delay. But he insisted on including his original sentiments on Social Security in his final speech. As delivered, the speech made a convincing case for what he had once proposed--so convincing that it was difficult for some viewers to tell that he was not pressing again for enactment of those springtime reforms.

Throughout official Republicandom, in Congress and in the White House, there is considerable apprehension over what will happen to this second, deeper effort at budget cutting.

The second round of cuts was needed, as one Cabinet member now concedes, mainly because administration officials miscalculated: They assumed that the financial community would react to the initial demonstration of resolve in cuts by lowering interest rates.

Now White House officials concede that political difficulties lie ahead. "Sooner or later, every administration has its legislative defeats," said chief of staff Baker, in charge of selling the program in Congress. "But . . . we will get a substantial portion of our package.

"What we end up with will be perceived as a political victory."