hatchet job

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A severe criticism or malicious verbal attack meant to ruin someone's reputation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun idiomatic A journalistic or other treatment which portrays its subject in a very unfavorable manner; a work of criticism which aims to destroy a reputation.
• noun idiomatic An action or a program which imposes deep reductions in expenditure.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a false accusation of an offense or a malicious misrepresentation of someone's words or actions