Correct punctuation to introduce a supporting quote

What is the correct way to punctuate the end of a sentence before a quote that directly supports the statement? I assume either a colon or a semicolon, but I have no idea which is correct.

For example:

Waldo is a better hide-and-seek player than Clem; "Waldo was the winner of the past ten annual hiding awards" (Where's Waldo 13).

Waldo is a better hide-and-seek player than Clem: "Waldo was the winner of the past ten annual hiding awards" (Where's Waldo 13).

(Excuse the silly example, but I didn't have a better one.)

Given your pair of possibilities, you would have to use the colon. A semicolon is just a lower-intensity kind of period/full stop, but a colon has an “→” (arrow) sort of relationship between the two sides.

For a quote that directly supports a statement preceding it, use the colon.

The semicolon is a break character, the colon is a leader. Use the colon. You would want to 'lead' the reader to the relevant reference, not create a short break at that point.

node18.html on the link provided in the answer by @Roaring Fish has some relevant info on use of semicolon vs. colon.

Some say the correct punctuation is a plain old comma. From the Purdue OWL:

Use a comma to introduce a quotation after a standard dialogue tag, a brief introductory phrase, or a dependent clause.

The detective said, "I am sure who performed the murder."`

As D.H. Nachas explains, "The gestures used for greeting others differ greatly from one culture to another."

Others say no punctuation at all, as the quotation marks do everything that is needed. From Larry Trask's "Guide to Punctuation" at the University of Sussex:

You should not insert additional punctuation marks into the sentence merely to warn the reader that a quotation is coming up: that's what the quotation marks are for. Hence the first two of the following are bad style, and the third one is wrong:

*President Nixon declared, "I am not a crook."
*President Nixon declared: "I am not a crook."
*President Nixon declared:- "I am not a crook."

Some newspapers use a colon - the Guardian, for example - but that is set by the individual style-guide for that publication and is not a rule as such.

The Purdue OWL says:

Use a semicolon to join 2 independent clauses when the second clause restates the first or when the two clauses are of equal emphasis.

Use a colon to join 2 independent clauses when you wish to emphasize the second clause, or after an independent clause when it is followed by a list, a quotation, appositive, or other idea directly related to the independent clause.

With that as our guide, either one could be acceptable, depending on what you are trying to do. Your opening declaration and the ensuing quote are both independent clauses; the second happens to be a quote related to the first.

Use of a semicolon would not "ungrammatical." However, if you were taking a poll, here's what I'd recommend: use the colon – it seems to be a better fit.