Pharoah, by his own choice, didn't want the Israelites to go anywhere. God didn't have to "make" him think that. He was self-hardened in that respect. Or "stubborn," if you will. That was his choice. God needed him to stay that way until He had accomplished His ultimate purpose through him. What purpose? For His name to be glorified and revered in all the earth. 2 or 3 plagues may have been enough to convince Pharoah's stubborn will. Don't you think you would have been convinced after the rivers turned to blood??? That would change anyone's mind. Not Pharaoh's! Why? God had judicially hardened him. He had sealed him in his disobedience, if you will. Even the most convincing signs and wonders wouldn't shake this man's resolve. Why? God had a purpose to accomplish through this man's hardened heart. (The Passover had to happen) This is what Paul is addressing in Romans 9. He is comparing what God did to Pharoah with what He was doing with the Jews of his day. How could these men see him put a guys ear back on and still kill him? How could they see him heal dozens of people, feed thousands more and cast out demons and not believe? Same reason that Pharoah couldn't believe Moses. They were being hardened. Pharoah was hardened so God could accomplish His will in the Passover, the Jews were hardened so God could accomplish His will with the atonement of the Passover Lamb. The Jews hardening was just for a time and it wasn't to keep them from salvation forever. Paul explains this in Romans 10 and 11 very clearly. He fully expects to see some provoked to jealousy and be saved. So, those hardened (as spoken of in Romans 9) are not the non-elect reprobates that Calvinistic doctrine tries to make them into. This is the greatest error of Calvinistic doctrine yet very few Calvinists are even willing to deal with it.