During a modern presidential election, the candidate for president of the United States selects a vice-presidential candidate based on factors such as demographics, ideology, popularity and presidential qualities. The two candidates then run for election as part of the same ticket.
A presidential candidate often considers a combination of qualities when selecting a vice-presidential candidate with the goal of improving the chances of getting elected. A vice-presidential candidate might be selected to bring geographic or ideological balance to the ticket to widen its appeal. For example, if the candidate for president is from New England, he might choose someone from the southern states as his running mate. Similarly, a conservative or liberal presidential candidate might select a moderate as a running mate.
Another consideration is electoral votes. If a presidential candidate needs to win a state with many electoral votes, such as California or Texas, he can choose a running mate from that state to increase the chances of winning. Popularity among groups of voters also contributes to the decision. For example, if the presidential candidate is not popular with urban voters, he might select a vice president who is. A presidential candidate might also select a running mate with traits that the candidate himself lacks to create a well-rounded ticket.