Final answer:
The correct word to complete the sentence is 'villainous,' as it describes the wicked or evil character of the candidate's intent.
Step-by-step explanation:
The correct form of the word villain to use in the sentence 'It appears this candidate has a ___________ intent in making comments about those running against him' would be villainous. When referring to the nature or character of someone's actions or intentions, 'villainous' describes something that is wicked or evil, which fits the context of the sentence as it suggests the candidate's comments are deliberately harmful. To vilify someone means to speak or write about them in a way that makes them seem utterly negative, which aligns with the meaning of villainous in this instance.