Ford was Vice President. He became President. It has been many years since we elected a Vice President in this country. The vote is for the President.
But don't underrate the Vice Presidency. Of the elections from 1956 on (excluding 1964, when there was no incumbent Vice President), there was only one (1976) when the Vice President was not his party's candidate either for President or Vice President. It seems that 2008 will be another exception, which is unfortunate.