Express your negative opinion towards someone who lacks integrity, values, honesty, decency, compassion, and authenticity, and argue that they are a disappointment not just as a world leader but also as a human being.
I would add to that (pathetic excuse)  :  not just for a world leader, but for everything else that makes a person a human being, such as integrity, values, honesty, decency, compassion, authenticity and several more I could come up with. He lacks all that and more and is just so very pathetic all around.