Section 3. If, at the time fixed for the beginning of the term of the President, the President elect shall have died, the Vice President elect shall become President. If a President shall not have been chosen before the time fixed for the beginning of his term, or if the President elect shall have failed to qualify, then the Vice President elect shall act as President until a President shall have qualified; and the Congress may by law provide for the case wherein neither a President elect nor a Vice President elect shall have qualified, declaring who shall then act as President, or the manner in which one who is to act shall be selected, and such person shall act accordingly until a President or Vice President shall have qualified.
First, we have no “President Elect” yet.
Second, McCain will wind up being the “qualified” person if Obama loses and if the required 270 electoral votes minimum go to him when the College meets. If it doesn’t get figured out by then, then its possible Democrats are elected and Obama isn’t President Elect and Biden becomes the temporary president until Congress can figure out who should be President.