Picking a running mate is one of the most important choices for a presidential candidate to make. Not only does the vice president sit "one heartbeat" away from the Oval Office, but he or she can help attract voters from key regions or demographics.

Vice President Dick Cheney has strengthened the office considerably during his tenure; the next vice president could also take an active policy role.

Presumptive Democratic nominee Barack Obama has organized a search committee to help find his running mate.