I'm not going to take credit for the ideas presented here. There was a documentary on TV called "The Real Jesus of Nazareth" that aired in Holy Week that hinted very strongly a this, but stopped short of spelling it out, probably for fear of offending Christians. I don't have anything to lose by angering the local sanhedrin, so in the next few paragraphs I'm going to present that scenario which assumes that Judas and Jesus conspired to fulfill messianic prophecy in order to bring down the priests and pharisees.
A couple of thousand years ago, two like-minded men met. One was Judas, a disgruntled former pharisee himself. He was a lightweight jewish Martin Luther who questioned the rigid observation of ritual and law and viewed the temple rites as a racket which supported the priestly class in luxury while bleeding the populace white. For instance, everything you did required an animal sacrifice. If you entered into a business deal, if you got married, if a child was born, you run to the temple where you buy a specially bred sacrificial animal, and then the priests kill the thing right in front of you. Apparently God takes the sacrifice's "essence" and the priests eat the leftovers. Not only that, the money you brought to the temple wasn't good enough. You've got to buy special temple money to buy the sacrificial animals. It goes without saying you're getting screwed on the exchange rate. And you can't provide your own animals, either. Noooooo, got to be specially raised AS sacrificial animals, 'course all that special care cost extry.
So Judas decided he'd try to put a stop to that horseshit.
The priests and pharisees had only two things going. First they had the sacrificial animal racket, and second, they were the keepers of the mystical secret knowledge that would identify the Messiah when he showed up. Thing is, once the Messiah shows up the bottom drops out of the sacrificial animal business and a whole lot of religious fat cats have got to go out and get real jobs. As you can imagine, the priests and pharisees had motive enough to contrive tests that would weed out everybody. There's that one test about dying and rising from the dead which is probably phony, probably slipped in to deter applicants. There were other signs. He would be directly descended from King David, a warrior, no broken bones or physical problems, blah blah blah.
Some of the signs were public knowledge. Some were rumor. Some were secret. Judas thought he knew enough of them that if he could find the right guy who would touch all the bases, the priests would have to declare him to be the genuine Messiah and then they could disband and then the Jews could stop wasting big hunks of their income on sacrificial animals and supporting an essentially parasitic religious institution.
So Judas had to find the right guy. Someone with the right pedigree from the right place. Someone who looked the part. Someone he could coach, who could both improvise and stick to the script. Someone who knew what was going on and was prepared to play a dangerous game with politically powerful interests in order effect a positive social change.
The guy he found was Jesus. Early on it was just the two of them. Not only was Judas a former pharisee, he was also the first desciple. That would have been the period during which Judas was telling Jesus what he was in for and all the hoops he'd have to jump through in order to force the priests to acknowledge him as the real McCoy. And that's the real trick, to force the priests and pharisees to put themselves out of business, forever relieving the Jews of a traditional financial burden.
Remember how people asked Jesus why he did this or that? Why he entered Jerusalem through the East Gate on a donkey, for example? He says, "I did it to make this prophecy come true. I did it to fulfill that prophecy." Remember how the priests and pharisees kept asking Jesus to say whether or not he was the Messiah? Remember how Jesus routinely insisted, "If YOU say so," or "That's for YOU to say." After all, it was THEIR job to peg him as the Messiah or not the Messiah. If THEY couldn't make the determination, then they didn't hold their social positions legitimately, and that might work just as well from Judas' point of view.
You can see how this might irritate the religious authorities, who are presented with two unpleasant options. As long as Jesus doesn't violate messianic prophecy they at least have to tolerate him. The people wouldn't stand for any action taken against a legitimate claimant. The longer he hangs around without being declared phony, the more the people are going to insist on a yea or nay from the muckey mucks. Jesus' strategy would have been to hang around in Jerusalem, fulfilling bits of prophecy here and there, and not get bounced on some prophetic pothole, and drag it out as long as possible. Once he makes a false step, though, they could lower the boom, which they eventually did.
So something must have gone wrong. Either Jesus stumbled publicly on some religious point while Judas was out of reach or Judas the disgruntled pharisee didn't have all the information he needed to coach Jesus into passing himself off as the Messiah. That might explain why Judas hanged himself after the crucifixion. Maybe he blamed his friend's death on his own failure or on some neglectful oversight.
If Jesus had hit all the notes just right, there would have been no keeping it quiet among the religiosi. Jesus did something to prove to the priests that he was not the Messiah. Otherwise there would have been a riot when the Romans nailed him up. Passover in Roman Jerusalem was always a volatile time. Trouble was always expected. The place was loaded with devout religious types. The authorities could not have kept the lid on Palestine after executing somebody who might yet prove to be the Messiah.
So where did the plan go wrong? You'll have to ask a pharisee.
Feedback from firstname.lastname@example.org
Sounds like somebody has rediscovered The Passover Plot (by Schoenfield, I think). He also wrote Those Incredible Christians which tells how Paul (a pharasee) took the religion of Jesus and made it into a religion about Jesus. There was also a book called The Jesus Party along the same lines. I remember these books as first suggesting to me that there was a lot more to the story than I had been taught in sunday school.