What constitutional rights are attached to a plea negotiation?

The most important right a defendant has in plea
negotiations is his fifth amendment right not to be a witness against himself. If/when
he enters a plea, he has waived that right. The above post emphasizes the importance of
sixth amendment rights, which is also important; but to me is secondary to a defendant's
right to remain silent. He does have the right to counsel, but most guilty pleas are
negotiated with the benefit of counsel. Before accepting a guilty plea, the defendant is
normally asked by the presiding judge if he is happy with the representation he has
received from his counsel. It should also be noted that by entering a plea of guilty, a
defendant has waived his right to a trial by a jury of his peers. Defendants are
normally reminded of this by the presiding judge so that the court may be satisfied that
the plea is entered into voluntarily, freely, and with full knowledge of the rights
available.