If a player whom is considering a call says, "I want to call..." ambiguously as he is deliberating, is this considered a binding declaration in Hold em?
This kind of thing is irritating at best and angle shooting at worst.
I suspect whether this is considered a binding action will depend on lots of context, such as the frequency he's been doing this and the intonation of his voice and the level of confusion of the other players in the hand after one of these incidents. Not all "I want to call" statements are created equal. For example, if he's tanking after a big bet into him, and he slowly says "I want to call" as part of some lengthy deliberations, I think you might reasonably assume that this doesn't qualify as stating an action. But if he's just casually saying "I wanna call" when any action's on him and he's thrown in chips after each statement, it might reasonably be interpreted as a call.
The real problem exists if this player is using this ambiguity to gain some sort of advantage, as in trying to discern the actions of players behind him while still trying to give himself a way out of a binding action. A good dealer and floorperson would help put a stop to any such shenanigans. As another player at the table here, you should be careful that you understand the real action in front of you before you act.
So, I think my answer here is a big "it depends." But the fact that you're even asking this question implies that this player was using this as a strategic tactic, which in my mind put it in the angle shooting category. When in doubt, clarify the action with the dealer, and if the player keeps it up, you might discuss it with the floorman.
If I was called over to the table to make a decision on this it could go either way. If the players were head up, they guy says I want to call ambiguously, and this causes the other player to turn up his cards, I would rule it a call. If their were other players in the hand and the next player to act after hearing the comment says I call to, I would tend to rule it a call.
If it was just ambiguous but did not cause anybody to act in some way, no harm was done I would rule it not a call most of the time. I might rule it a call depending on the factors of the player, like Chris said, how often, how ambiguous, the inflection in the voice etc.
As a player I don't mind a player pulling this kind of angle to much. I am seasoned player, and they are going to have more downside then up. Most of these moves are weak, and the weaker the player is the better the moves work against them. Not to say they do not get irritating, and old.