In an editorial today, "Senator McCain's Choice," the print edition of the New York Times included this passage:
Governor Palin’s lack of experience, especially in national security and foreign affairs, raises immediate questions about how prepared she is to potentially succeed to the presidency. That really is the only criteria for judging a candidate for vice president.
It's criterion, the singular form of this Greek noun. Phenomenon is another singular noun that's often erroneously mixed up with its plural, phenomena.
The Times's error was corrected in the online edition.
By the way, the "split infinitive" in the editorial--to potentially succeed--is perfectly acceptable. See this Language Log post for more about that hoary grammatical fallacy.