John McCain was not born in the United States of America but rather born in Panama to US Citizens while his father served in the navy which appear to eliminate him from serving as President.

Here's what the constitution says regarding eligibility for the Presidency.......

"Article 2, Section 1, Clause , No Person except a natural born Citizen, or a Citizen of the United States, at the time of the Adoption of this Constitution, shall be eligible to the Office of President; neither shall any Person be eligible to that Office who shall not have attained to the Age of thirty five Years, and been fourteen Years a Resident within the United States."

The exact definition of "A natural born Citizen" is unclear as stated in the Constitution but as there were no foreign military bases at the time and with the founding fathers' distaste for foreign intervention being clear it seems unlikely they meant anything other than a person having been born in the United States.

The 14th Amendment touches on the same issue and states "All persons born or naturalized in the United States, and subject to the jusrisdiction thereof, are citizens of the United States wherein the reside". You'll notice it says "All persons born in the United States"

That there are two types of U.S. Citizens....
1) Citizens born in the United States.
2) Naturalized US Citizens.

We must presume McCain is the latter as he was clearly not born in the United States (A military base in a foreign country is not soverign US territory.) leaving one to conclude that McCain is actually a 'Naturalized Citizen' and thus ineligible to be either President or Vice President.