California senator Kamala Harris gave a powerful acceptance speech on Wednesday at the Democratic convention. While her selection has been widely framed in terms of her being the first bi-racial vice-presidential pick in US history, she also stands a good shot of becoming the first female US president too.

A key reason why Joe Biden’s decision to select her may become one of the most consequential choices of running mate in decades is partly because he will be the oldest person to assume office in January, at 78, if he triumphs over Donald Trump. She could easily be the next but one holder of the top office in two scenarios. That is, either Biden passes away or is incapacitated in office, or she could well run for the presidency after a Biden term because the vice-presidency has become perhaps the single best transitional office to the Oval office.

Biden searched high and low for the strongest possible pick to provide momentum against Trump in one of the strangest ever election years in US history. Aside from the election impact of his decision, another factor he considered in choosing Harris is that the electoral stakes have grown – in the nuclear age – of not selecting a deputy who is perceived to be capable of assuming office effectively upon the incumbent’s unanticipated death or incapacity. This is especially important for Biden given his age, with Harris potentially only a ‘heartbeat’ from the presidency from January.

History underlines the crucial role that vice-presidents stepping up to the presidency have played. Perhaps Harry Truman best exemplifies this.  Within weeks of assuming office in 1945, after Franklin Roosevelt’s death, Truman had to make several hugely consequential, controversial decisions, including the atomic bombing of Hiroshima and Nagasaki.

In this context, Biden has sought to make a choice that will ‘do no harm’ to his prospects and avoid the mistakes that others have made (Harris as well as serving as a California senator was also formerly the state’s attorney general). Take the 2008 election when Republican nominee John McCain, then aged 71, selected Sarah Palin – whose only major experience of office was less than two years as Alaska governor. Rather than boosting McCain’s campaign Palin was – ultimately – widely viewed at the time as too inexperienced to be able to potentially assume the presidency if McCain passed away, or was incapacitated.

Historically, the process of selecting vice-presidential nominees has tended to be fashioned around issues like reconciling important party stakeholders after potentially bruising nomination contests; and the perceived advantage of cultivating ‘balanced tickets’ in which the vice-presidential and presidential candidates were differentiated by factors such as their ‘home’ region so as to maximise support across the nation.

However, partly because of changes in the presidential nomination system, and indeed the proliferation of mass media, these traditional considerations – while still of consequence – are less relevant to the modern process. For instance, Al Gore was selected in 1992 by Bill Clinton (a fellow centrist Democrat and southerner) not to balance the ticket, but to reinforce the narrative about Clinton’s ‘New Democrat’ change candidacy.

The Californian, bi-racial Harris (the daughter of Jamaican and Indian immigrants) has several ‘balanced ticket’ credentials for Biden (whose home state is Delaware). Yet, she also reinforces his centrist political credentials, just as Gore did with Clinton in 1992.

Biden reportedly wants Harris to have the same sort of close relationship with him as he had from 2009 to 2017 with Barack Obama who also spoke at the convention on Wednesday. If so, this would see Harris become a potentially powerful vice-president.

Biden has also deliberately selected a candidate who is a generation younger (Harris is 55) with chances of being a future presidential candidate later this decade or even in the 2030s. Since 1960 four sitting vice-presidents (Richard Nixon 1960, Hubert Humphrey 1968; Walter Mondale 1984; Gore 2000) won their respective party’s presidential nomination but then lost the general election, whilst two have been elected president (Nixon 1968 and George HW Bush 1988). Biden hopes to be the third in November. It is plausible, if so, that Harris could follow, becoming the first female president to boot.

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