I dont know why they are waiting so long. After all, the party gave Leonel powers to choose whomever he wanted. I were Leopnel, and I would have chosen my VP aboput a week or two ago, give the impression of complete confidence and unity from within.
Now, the longer he waits the more speculation it arouses. People will start to ask why is he waiting so long? If the candidate he chooses does not have charisma as time passes and expectations grow, the damage could be worse than if he had chosen that candidate weeks ago when that subject was not as important and the expectations where alot less.