The triumvirate of the Grand Old Party met quietly this spring to discuss what to do about President Carter's Mideast jets package.

House Republican Leader John Rhodes came to the meeting favoring the plan. Senate Leader Howard Baker came to the meeting noncommittal. Republican National Chairman William Brock came to the meeting to talk the other two into opposing it.

Brock argued the case on its merits but mostly on its politics. The American Jewish community strongly opposed the package because it wouldmean providing American jets - 60 F15s - to Saudi Arabia. If the Republican leadership stands united in its opposition to the Carter package deal, Brock argued, the GOP would be able to finally drive a wedge between the Democratic Party and the Jewish vote (read this also "Jewish money"). And for the Republicans, currently mired in a rebuilding year, this had all the attraction of the land of milk and honey.

Brock's persuasion turned John Rhodes around on the issue, according to informed sources. But the big vote was scheduled for the Senate. And there, Howard Baker - much to the disappointment of Brock and other Republicans - helped Jimmy Carter carry the day. Once again.

Carter has had two glittering victories in the Senate since his inauguration: the Panama Canal treaties ratification and the approval of his Mideast president owed his success most of all to the Republican leader.

On both occasions, Baker cast his votes against his own political interests. He has brought sizable political problems down on himself with his actions. On the Panama Canal, Baker has found himself subjected to vitriolic attack from the Republican far right. On the jets package, he has cost himself a chance to gain important support from American Jews who are disenchanted with Carter, and he has left some of the pros in his own party disenchanted over what they see as a once-in-a-political-lifetime opportunity lost. But Baker voted the way he thought was right regardless of the political repercussions, and this is a rare enough measure of leadership these days to warrant special attention. Rare enough, even, to warrant a brief personal plug.

"I hope this doesn't sound unduly noble," Howard said with due nobility in an interview the other day, "but I think it came down to both what is best for the country and what is best for the Republican Party in the long term. And what I am saying is that for the party and for me, the right decision was the best decision in the long run." He paused. "But in the short term, it has caused me some political problems."

Short-term political problems. "I think it cost him the [presidential] nomination," says Rep. Philip M. Crane (R-Ill.), chairman of the American Conservative Union. "Most conservative voters vote in the primaries." He added, with a no-pun-intended deadpan, that conservative Republicans "tend to have elephantine memories."

Baker is hoping that time heals all wounds, even though he knows some conservatives are determined to show time wounds all heels. Currently, Baker is taking a conservative stance on matters ranging from the labor law reform bill (he's leading the Senate fight against it) to strategic arms limitation talks (he's even out-scooping Washington's Democratic Sen. Henry M. Jackson in demanding that Carter be more hard-line with the Russians.)

But this is not the true political talent of Howard Baker. He is at his political best when he is carefully sculpting a middle ground out of one or another of the extremes. He has done it time and again. He did it, in fact, in both the Panama Canal and Mideast jets issues.

Panama Baker held his ground for months, during the early going, as the political tides ebbed and flowed around him. Then he made a personal inspection trip to Panama and declared that he had discovered that U.S. national-security interets required two further amendments spelling out U.S. rights of prior passage of ships and the right to defend the canal. Thus, having staked out a position somewhere to the right of Carter - more palatable to many Republicans - he went on to work vigorously for the passage of the amendment Panama agreement. He brought several Republicans with him, Carter officials concede, and was personally responsble for Carter's one-vote victory.

Jets . Oil companies were pushing quietly for the Carter jets package, but the Jewish lobby was pushing vocally to defeat it, when Baker went on "Face the Nation" and suggested that there ought to be some sort of compromise. He proposed several ways to "tinker with the package a little" and emphasized that there is a special relationship between the United States and Israel, even though the Saudis did need those jets. The result, worked out with other senators and the White House, was a sweetener for Israeli shipment, plus assurances about the Saudi use of the F15s they would be getting. Then Baker voted against the pro-Israeli lobby.

Is Baker's artfully ability to carve out a middle ground a matter of politics or a matter of dealing strictly with the issues on their own merit? "Well, that is a hard question to answer," Baker says. "Those two things are so intertwined that it is hard to separate them. None of the suggestions I made were strictly done on a matter of politics. But then all of them have taken into consideration the political facts of life."

The facts of life about Howard Baker are that he wants to run for president in 1980. But first he must make sure that he is re-elected to the Senate in November (at present he seems a heavy favorite). After that, his inclination is to try to keep his post as minority leader in 1979, while he goes through the formality of deciding once and for all that he will make the run for the White House, according to sources close to Baker. He plans to promise Republican senators that once he decides definitely (perhaps midway through 1970) he will let them know and then they can elect a new Senate leader while he goes all-out to win the presidential nomination.

Baker's advisers say they are still discussing whether the senator canrun for president and continue as minority leader. "It's still an open question," said the minority leader's administrative assistant, James Cannon, who has previously served as an adviser to Gerald Ford and Nelson Rockefeller.

One wall in Cannon's office is dominated by a map that hints at the answer. The map of the United States is studded with different colored pins showing Baker's travels in 1977 and 1978. Baker made 38 visits to places outside Tennessee in 1977, but this year, what with his campaign needs back home and his increased burdens as minority leader, Baker has made just five stops around the United States (two of them being to Baker fundraisers in Palm Beach and Palm Springs where GOP retirees go to get tanned and GOP politicians go to get green).

Senate Republican grumblings may make the answer even more clear. For some Republicans complain that Baker is already overscheduled and underorganized. There was the time, for instance, that Baker was expected to appear at a key Senate Public Works Committee meeting for the makeup of a clean-water bill. He didn't show because he had been scheduled to be elsewhere giving a speech at the same time. Sen. Robert Stafford (R-Vt.), a Baker supporter, was among those upset by the minority leader's no-show.

While the Baker men ponder the conflict between Senate leadership and presidential candidacy, and try to smooth the conflict with the conservatives, political advisers down at the other end of pennsylvania Avenue - in a rather rare gesture by Washington standards - give creidt where it is due. "I'll tell you something about Howard Baker," said one of Jimmy Carter's most senior assistants. "Howard Baker is a damn statesman." He paused. "But you'd better not put my name down alongside that quote. I mean, after all, we all know what his future plans are."