Is it "who to blame" or "whom to blame"?

A little morei

"You blame him," not "you blame he" — the him-test tells you the object form fits. So the phrase with whom is the grammatically careful one. In casual speech, "who to blame" is widespread and most readers won't notice.

The full entryii

More quick answersiii

• → What's the difference between "who" and "whom"? Who is the subject — it does the action. Whom is the object — the action happens to it.
• → When do I use "whom"? Use whom when the pronoun is the object of a verb or preposition — when something is done to it.
• → Is it "who should I call" or "whom should I call"? Strictly, "whom should I call" — the caller is doing the calling to someone.