Who do the Democrats prefer? Whom do the Democrats prefer? Which sentence is correct ?
Whom.
Turn the sentence around and make it a statement.
The Democrats prefer whom. It's clear that whom is the object of the verb "prefer."
Whom can you believe? You can believe whom
You would use whom because it is an object of the verb. Is this correct?
Yes, "whom" is correct in that question.
Both sentences are correct, but they have slightly different grammatical structures.
The first sentence, "Who do the Democrats prefer?", uses the interrogative pronoun "who" as the subject of the sentence. This is a question asking for the identity of the person or group that the Democrats prefer.
The second sentence, "Whom do the Democrats prefer?", uses the interrogative pronoun "whom" as the object of the preposition "do". "Whom" is used when referring to the object of a verb or preposition.
In terms of meaning, both sentences are asking the same question about the preference of the Democrats. However, in contemporary English, the use of "whom" has become less common and is often replaced with "who" in many situations, even when it would technically be more accurate grammatically to use "whom".
So, to answer your question, both sentences are correct but the first one using "who" is more commonly used in modern English.