Presidents do not usually launch their reelection campaigns while flying over Brazil, and Ronald Reagan is no exception.

Those close to Reagan are saying in the wake of Lyn Nofziger's call to conservatives to plan the 1984 campaign that the president, as Nofziger well knows, is not a person to be pushed.

And the flap over Nofziger's letter to a score of conservative political consultants calling them together for a reelection planning session today annoyed Reagan because it seemed, as one source described it, to be "unseemly pressure " on the president.

This source, and several other high administration officials, believes that Reagan is likely to decide to seek another term.

But he adds that Reagan has not, in fact, made any decision and doesn't at this point want to be pressured in either direction by anyone.

Reagan, publicly gentle with former aide Nofziger while privately deploring the letter, said as much himself on Air Force One returning home to Andrews Air Force Base from Honduras Saturday. Asked whether Nofziger was overanxious to get him reelected, Reagan replied: "I don't know. I'm right in the position I always was, which is that no decision has been made -- honestly, that's true."

The rest of the dialogue on Air Force One is instructive. In response to a follow-up question about whether he will run again, Reagan repeated an old bromide in which he believes: "As I've said before, the people tell you whether you do that or not."

And when a reporter wanted to know what wife Nancy is telling him, Reagan said, with a smile: "She likes me. She thinks that this isn't the time to make such a decision."

Whatever else Nofziger's Nov. 22 letter may have failed to accomplish, it succeeded in reigniting lingering animosities between true-blue Reaganites and those they call "the Bush wing" of the party. The letter's most incendiary comment was the concluding phrase of a sentence: "it is important that the next presidential election be a Reagan-Bush campaign, not a Bush-Reagan campaign."

Within the White House, this was seen as a slap at White House chief of staff James A. Baker III, who managed Bush's campaign in 1980, and at former Bush supporters in the administration and at the Republican National Committee. Baker, backed by the president and deputy chief of staff Michael K. Deaver, responded by ordering administration officials not to attend the meeting called by Nofziger.

The result, as one conservative acknowledged yesterday, is that the meeting is likely to fan hostilities within the party rather than promote Reagan's reelection. "Lyn meant well, but he should never have written that letter," says a Republican activist who has been close to Nofziger.

Nofziger, incidentally, has the reputation of rarely forgetting old scores. He showed it in a postscript to the letter that said: "P.S. I have no desire to run this thing. We can put anyone in charge you-all want. But if it's Sears, count me out."

This, of course, is a reference to John Sears, whom Reagan fired in 1980 and certainly won't ask to run a future campaign. But those who know the president best don't think he'll ask Nofziger either.

Illinois conservatives unhappy that Reagan intends to keep his commitment to attend a fund-raiser for Republican Sen. Charles H. Percy next year have come up with a ploy to put the president on the spot. Their plan is to schedule a fund-raiser for Percy's most likely GOP challenger, Rep. Tom Corcoran, on the same night and invite Reagan to come as a matter of fairness.

One of the hallowed public relations techniques for dealing with an unfavorable story is to put out another story that will top the bad one. Some members of the White House press corps believe that's just what happened last Friday night in Costa Rica, when President Reagan -- hours after he had been told off in public by Colombia President Belisario Betancur -- announced that El Salvador is doing just swell on human rights and deserves to have its military aid renewed.

But White House officials insist that Reagan was simply asked the question and blurted out the answer, as he is apt to do. Whether it was a designed tactic or not, the president's announcement did squeeze the embarrassing Betancur story to a secondary status in some accounts and pushed the story off the front page of The Washington Post.

Reaganisms of the Week: A tie between the president's salute to "the people of Bolivia" while in Brazil and his discovery that Latin American nations "are all individual countries."

The nonexistent award for the best printable wisecrack of the Latin American trip goes to the Chicago Tribune's Steve Neal, who observed of Reagan-loving Costa Rican President Luis Alberto Monge: "He's spent more time in Washington than Ed Meese."