Rivka's Dilemma
Rivka, overhearing Yitzchak's intention to bless Esav (27:5), faces a dilemma.

Does Yitzchak plan to bless Esav with the bechira (or that God grant him the bechira)? If so, she must act quickly, for the future of Am Yisrael rests on her shoulders.
Does Yitzchak think that both children are chosen? Is he giving a bracha of leadership to Esav? The result of this blessing could also be disastrous!
Can Rivka just go over and tell Yitzchak that he is making a mistake? Is it too late? Will he listen? Would he be willing now, after so many years, to change his perception?

Rivka has limited time to act, yet feels responsible to the prophecy which she had received, and hence obligated to rectify the situation. In her eyes, this may have been the original reason why God had originally granted her this knowledge. Unfortunately, however, Rivka must resort to trickery to make sure that Yaakov will receive the blessing instead.

Now that we have explained Rivka's course of action, we must now explain Yitzchak's.