Vice president

The vice president's primary duty is to succeed to the presidency in the event of the resignation, removal or death of the incumbent president.

The first vice president, John Adams, described the position as a "most insignificant office"

The vice-president's only other constitutional responsibility is to preside over the US Senate and to use his vote as the decider in the event of a tie.

This is only overridden when the Senate is conducting an impeachment trial against the president.

Early vice-presidents had little else in the way of official responsibilities.

In 1885 Woodrow Wilson, who would later become president, commented that there was "little to be said about the vice president... His importance consists in the fact that he may cease to be vice president."

In recent years however vice presidents have taken on an increasingly prominent role managing a range of high-profile foreign and domestic policy programs.