Overriding could also be "passando por cima/ignorando":
...is how Trump's inflammatory campaign rhetoric continues to define him, overriding his new administrations' efforts to cast his presidency in more positive ways."
...é como a retórica da campanha de Trump continua a defini-lo, passando por cima dos esforços do seu gabinete em descrever/apresentar/mostrar/divulgar a sua presidência de uma maneira mais positiva.
Verb To cast someone in a particular way or as a particular thing means to describe them in that way or suggest they are that thing.
Democrats have been worried about being cast as the party of the poor... V n as/in n
Holland would never dare cast himself as a virtuoso pianist. V pron-refl as/in n
(Source: dictionary.reverso.net/english-cobuild/cast )