Well, the Paladin and the Cleric probably aren't very vulnerable to being controlled by the Telepath in most cases, especially the Paladin, with his high saves. Also, unless you have house ruled the "displays", people will be aware of the fact he is casting spells, and if he fails to control someone, they should be aware that an attempt was made.
There's really not much you can do but let nature take it's course, here, unless you want to get the other players involved. The Telepath will have to be careful, or he could incur the wrath of his fellow party members. If you really want to try and prevent that from happening, I
suggest giving him a taste of his own medicine.

Introduce an NPC for a short time that "pushes" him the same way he pushes the other party members.
He should realize how annoying/infuriating (depending on personality type) it is to have other people control your actions, and hopefully will refrain from such actions in the future. Barring that, I would ask the rest of the players what they think of his actions, and what the other characters think of what he's doing.
If any of the characters are particularly free willed or spirited, they will probably take offense at the Telepaths actions, and bring him to task about it. If the characters don't confront their fellow party member about these actions, he will assume he is free to do as he wishes, and will continue to do so until he either gains full control of the party or it reaches a boiling point and a civil war develops between the party. Both are not very desirable outcomes.