In a city where politics is a year-round spectator sport, there is no better entertainment than the mad scramblings of senators and presidents who have leaped before they looked. So welcome, sports fans, to the climax of the great AWACS "debate."

The question now is whether the Senate should veto the $8.5 billion sale to Saudi Arabia of five airborne warning and control systems aircraft, together with fuel tanks, tanker aircraft and air-to-air missiles to "enhance" the range and firepower of some 60 F15 fighter- bombers already cleared for sale to the Saudis.

The outcome might not even be in doubt if a significant number of congressional opponents of the sale had not quickly collapsed in the face of a full-court press by Israel's American supporters that began a full six months ago. The same may be said if the administration had not been rolled over by a Pentagon drive for approval that began back in the Carter-Reagan transition days.

By the time the Reagan administration looked up from its economic program to confront the AWACS challenge--not much more than a month ago--the House was a wipeout. And at least half the Senate, where the struggle centers this week and next, had locked itself into seemingly solid opposition. (Both houses have to disapprove in order to block the sale.)

Result: serious discussion of the real issue, as it now stands, has given way to second-guesses, strong-arm maneuvering, irrelevancies--and acrimony. To cite the self-evident impact of the Israeli lobby is to impugn motives. Anwar Sadat's assassination becomes a pretext for swinging either way: for supporting the president at a time of high Middle East uncertainty, or for shying away from all entanglements with "unstable" Middle East regimes.

At one point a search was on for ways to bottle up in committee the Senate resolution opposing the deal so that nobody would have to choose between offending the White House and offending Israel. "There are plenty of people," says Sen. Larry Pressler (R-N.D.), "who would rather not vote on the AWACS controversy."

That might be a safe way out for scrambling senators. But there is a real and urgent issue here, and it has nothing to do with what should have been done. Even sympathetic Republican senators will tell you that as a matter of political tactics, the administration's case "could have hardly been handled worse."

But that doesn't get you away from where we are with the Saudi AWACS deal, how we got there, and what would be the consequences if the deal falls through.

The issue is nothing so simple as whether Saudi Arabia "needs" AWACS, and still less whether the Saudis will be nicer about oil or Camp David if they get them. The most you can say about that is that the more influence the United States has with Saudi Arabia the better; and that whatever influence the United States has will be measurably diminished if, at this stage, the AWACS commitment is withdrawn.

And this leaves aside the prospect that Saudi Arabia can acquire roughly comparable equipment elsewhere, and on terms that would deny the United States a restraining hand--or any participation in its use. The question comes down, then, to an American need. We got where we are because, at the outbreak of the Iranian- Iraqi war, the United States sold Saudi Arabia on the need for four American AWACS to overfly its territory, for the same reasons that AWACS are on station over NATO territory: by helping to detect surprise attacks, they also serve to deter. Recent Iranian air attacks on Kuwaiti oil fields reinforce the argument for some sort of aerial surveillance of the Persian Gulf.

It would be convenient if the Saudis would leave things as they are. But they are entitled to both pride and practicality. Hospitality to "Western Imperalist" military forces plays into the hands of the extremists in the Arab camp; it contributes, that is, to Saudi "instability."

That doesn't remove the "instability" issue-- the threat to Israel, the possible loss of sensitive high technology to an enemy. But actual delivery dates are at least five years away; for many more years Americans will be on hand, closely involved, with the next-best thing to an American presence on the ground.

It's risky. But so is the present arrangement --which even opposition senators endorse. Those American AWACS parked on Saudi Arabian airfields are not invulnerable to Saudi "instability," either.