This could be due to death, resignation, or impeachment. Before the passage of the 25th Amendment, it was never constitutionally clear who would serve as president in any of these situations. Once the vice president assumes the role of president, the new president must choose a new vice president, from the same party, and have that person approved by Congress. An example of this is when Vice President Cheney assumed the role of President from George W. Bush in 2002 and 2007 in order for President Bush to undergo colon.