DENVER -- John McCain is turning up the heat on Barack Obama and his new running mate, Senator Joe Biden.

Although McCain calls Biden a “wise selection” and admits he’ll be formidable, he’s critical of the Obama-Biden ticket on foreign policy. The Arizona Republican tells CBS News that he disagrees with Biden’s decision to vote against the first Gulf War, as well as his position that Iraq should be divided “into three different countries.”

Also, a new McCain ad questions Obama’s motives in passing over his former chief rival, Senator Hillary Rodham Clinton, and settling on someone who fared far worse in the primaries.

The ad features clips of Clinton saying critical things about Obama during the primaries.

A voiceover announcer asks, “Who won millions of votes but isn’t on the ticket? Why? For speaking the truth.”