Excerpt from Dr. James White's book "The Potter's Freedom" (pages 211-214):
For the Scripture says to Pharaoh, “For this very purpose I raised you up, to demonstrate My power in you, and that My name might be proclaimed throughout the whole earth.” So then He has mercy on whom He desires, and He hardens whom He desires. Romans 9:17-18)
The example of Pharoah was well known to any person familiar with the Old Testament. God destroyed the Egyptian nation by plagues so as to demonstrate His might and power in the earth, and key to this demonstration was the hardening of Pharoah's heart. Before Moses had met with Pharoah the first time God told him:
When you go back to Egypt see that you perform before Pharaoh all the wonders which I have put in your power; but I will harden his heart so that he will not let the people go. (Exodus 4:21)
It was God's intention to bring His wrath upon the Egyptians. God's actions were not "forced" by the stubborn will of the Egyptian leader. God said He would harden Pharoah's heart, and He did. Listen to the impudent response of this pagan idolater to the command of Moses: