Possibly both, but the madness is more relevant than the senile. Senility would be purposeless, but the madness has a passionate and malignant intensity.

Senility would be progressive. He has been acting the same way since coming into the public eye. We see it somewhat more now than in his first term, where he had to hire experienced hands to execute things, and they put a damper on some of his worst ideas. In his second term, he feels beholden to nobody, and his friends are happy to do exactly as he wants.