absolute power corrupts absolutely.  (i.e. controlling every lever of power in government will give you the impression that you are utterly unbeatable and lead you to do things that you otherwise would not be so foolish to even contemplate, much less attempt to implement, like nominating a wholly-unqualified person to the highest court in the land)

it doesn't matter the political affiliation, although one hopes that certain political ideologies are less susceptible to the corrupting influencing of power, i honestly think that it ain't that way.