They never promised us a slide show.

No, but they did keep dangling the possibility in front of us.

When, with a look of unveiled disgust, Senate counsel Arthur Liman completed his interrogation of Lt. Col. Oliver North at the Iran-contra hearings yesterday afternoon, the proceedings began to deteriorate as a television spectacle, and Oliver North's magnetism showed signs it might be petering out at last.

The reason was, the lawyers finished up, and members of the committee began their own questioning. Having read the public opinion polls and the handwriting on the TV screen and having perceived North to be a great big wow with the viewing public, the congressmen behaved as though they plan to hit him with nothing harder than a powder puff.

This revoltin' development made all the more inviting the prospect of a slide show, Ollie North narrating, that came up earlier. It's a production North used to give to potential sympathizers to the contra cause, and committee members have called for a command performance. But Sen. Daniel Inouye (D-Hawaii), chairman of the Senate committee, announced after the noon recess that some of the slides are classified and thus raised the specter of a TV blackout.

And then, sounding a bit like the organizer of a Shriners' smoker, Inouye said, "We will get a room." Whether the slide show would ever be televised became doubtful; it clearly wasn't going to happen yesterday.

ABC's Peter Jennings hailed North's willingness to do the slide show as "a stroke of genius." Of course; it would be one long contra commercial, and yet TV viewers would be inescapably glued to it.

"We may have reason to laugh and chuckle," Inouye said a moment later, "but what has been brought out, to date, gives me little reason to laugh." No, no laugher he. But surely it's North, the master disarmer, who's entitled to the guffaws. The committee couldn't wait to get him, and now, it must have occurred to some members, it would be great to get rid of him.

The longer he stays, the more beloved he seems to get with viewers, and the shorter their patience grows with Congress. About the most that can be hoped for from future questioning is redundancy. There's nothing to be gained for committee members except getting their kissers on TV, and the contest may be to see which member can give North the biggest and most indelible smooches.

Surely the wrongest prediction of the day belonged to Phil Jones of CBS News, who told Dan Rather that once Liman finished up and the committee members took over, "you're going to see the partisan bickering really start here." There was some bickering to begin the afternoon session, but it was divided along House-Senate lines rather than party lines.

Rep. Bill McCollum (R-Fla.) whined that Liman had committed "egregious" partisan questioning in the morning and said his job was to get at the truth and "not to slant biases." Push came to push and a few members squabbled, partly over remarks by Sen. David L. Boren (D-Okla.) on a CBS News late-night special Thursday. Boren had griped that committee counsels had taken up too much time and indicated the members were itching to have a go.

Two members had their chance yesterday after Liman retreated, one of them a Democrat, and they stopped short only of inviting the Norths over for drinks and dinner. The deference was appalling. North appeared to revel in it, and cranked his righteous glow up a few notches until it looked as if he were posing for an inspirational wall hanging. Maybe a decorative plate. He does like to fold his hands prayerfully every now and then.

Thus we got a glimpse, a rather enormous glimpse really, of what finally may do Ollie North in. That old devil ego. Virtually invited to speechify by Rep. Ed Jenkins (D-Ga.) and Rep. Dick Cheney (R-Wyo.), North accommodated. He charged up the hill again. And again. Of one operation, he recalled, "And it all worked like clockwork, and everybody smelled good when it was done."

He invoked God a lot, eyes aglisten. The piety was sliced pretty thick.

Suddenly, North didn't seem like Jimmy Stewart so much any more. He seemed more like Charlton Heston.

True, the bandwagon is rolling almost out of control now. Rather showered North with accolades. He spoke, with correspondent Bruce Morton, of "an Oliver North movement" taking shape in the country, even including a bid for political office supposedly being advocated in the congratulatory wires that North hammily displays on the desk in front of him.

"A Jack Kemp-Oliver North team is being talked about in some of the telegrams, so away we go," said Rather.

"Not by Jack Kemp, so far, I think," said Morton, smiling patiently and implying with his smile that Rather ought to put a sock in it.

Earlier, Jones had reported a "death threat against Oliver North," supposedly by a foreign terrorist organization with agents in Washington, but it's not a story the other networks were inclined to run with.

When he and the missus left the Senate caucus room, North did not do his usual routine, stopping at an open mike to thank those tens of thousands of Americans for their support. Perhaps even he realized it was all getting a trifle sticky. Maybe his lawyer tells him when he's going too far during their frequent cuddling huddles.

Everyone is saying that North is the most effective and eloquent spokesman for Ronald Reagan's contra policy ever. A greater communicator even than Reagan, at least on this subject. This leads to a hypothesis so far not pursued. What if the administration contra corps actually wanted the scandal uncovered, made it happen so it had to be uncovered (hence the flagrant shredding sessions), and knew all along they'd be dispatching North to look longingly and plaintively into network TV cameras for days and days on end at congressional hearings deemed inevitable?

It remains to be seen whether North has reached the point of diminishing returns in the popularity polls and whether the hearings will now become so dull and lovey-dovey that people will tune out. Keeping one of North's pronunciation quirks in mind, it may be time to start singing, "You say cone-tra, and we say contra . . . let's call the whole thing off . . ."