Constitutional FAQ Answer #81
Q81. "In current usage, both the President and Vice President are elected on the same ballot. Does the Constitution as currently amended allow for these executives to be from differing parties?"
A. The Constitution neither prohibits nor encourages the two be from the same party. They are voted on separately in the electoral college, so theoretically, the President and Vice President could be from different parties. However, many states have laws which force their electors to vote for the candidates that the winning party has chosen. There is question about whether an elector could be prosecuted for doing whatever they want once the election is over, but the point is mostly irrelevant - the party that wins picks the electors, who are generally party loyalists, so are unlikely to vote against the party.