What happened to Par'oh?

Parshat Va'Era

By all the plagues the Torah describes in fairly thorough detail what happened and how Moshe warned them and how they beseeched Moshe to remove the plague. The 2 exceptions to this seem to be dever and sh'chin. The description of the actual plague and how Moshe delivered it is fairly descriptive, but after describing it the Torah then just simply tells us that Par'oh "hardened his heart" and did not send out the Jews.

Why did he not beseech Moshe to remove these plagues, as he did in the plagues prior to those and he will do in the plagues after those? Were these plagues not so bad that he did not feel the need to beg Moshe to reverse the plague? Did he not or was the Torah just using brevity as a style of writing? If the Torah was being brief, why only in these 2 plagues?

I do not, at this point, have a satisfactory answer to these questions.

If you have an answer, put it in the comments, or email me at israeli.jew@gmail.com