What is the electoral college and how does the map work? US voting system explained

A look at the unique American system of electing a president and why it is controversial

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The race between Vice President Kamala Harris and former president Donald Trump is tight but who will win on Tuesday depends not on the popular vote, but on the electoral college.

The US is the only democracy in the world where the head of state is chosen by an electoral college. The National takes a look at what that is and how it works:

What is the electoral college?

The electoral college is a national body consisting of 538 members who are responsible for electing a president. The writers behind the Constitution set it up to give power to the states and avoid having Congress decide the winner.

Each state's electors usually cast their votes for the candidate who won the popular vote in their state, and the runner-up gets nothing.

Some states, such as Nebraska and Maine, have elector votes awarded based on congressional district and statewide results.

To win the presidency, a candidate must secure 270 electoral votes nationally – the smallest majority of the 538 possible votes.

Why is the electoral college controversial?

In most elections globally, a candidate wins an election based on the number of votes they receive.

Under the electoral college system, more weight is given to a single vote in a small state than to the vote in a large populous state, leading to results in which the winner of the election is not always the winner of the popular vote.

It also affects how candidates campaign: nominees tend to focus most of their efforts on battleground states, which can “swing” different ways politically, instead of reaching out to voters in solidly Republican or Democratic states.

Hillary Clinton won the popular vote in 2016 but Mr Trump won because he carried the electoral college. In 2000, George W Bush secured an electoral college win despite Al Gore having won the popular vote.

Democrats say the system favours Republicans since Democrats have won the popular vote more often and Republicans often take less-populated states with more electoral votes.

There have been growing calls for the end of the electoral college, and for a simple majority vote instead, but such a change would require a constitutional amendment and it is not clear whether there is enough support or interest to make that happen.

Who are the electors?

They can be former or current party officials or political activists chosen by parties in the state. Members of Congress are not allowed to serve as electors.

Each state has as many electors as it has representatives and senators in Congress: there are two senators for each state and the allocation of seats in the House of Representatives varies according to population size.

California – the most populous state – has 54 electors, while the six least populous states and the District of Columbia have only three.

But this apportioning means that one electoral vote in Wyoming – the least populous state – represents about 192,000 people, while one vote in Texas – one of the most underrepresented states – represents about 730,000 people.

How and when are the votes counted?

After state election officials certify ballot tallies, the electors meet in their individual states and certify them to officially cast their votes. They will send their votes and results to Congress on December 17, a little more than a month after the election.

The candidate who wins 270 electoral votes or more becomes president.

Those votes are officially tallied by Congress in a special session on January 6. The vice president presides over the proceedings as the envelopes for each state are opened and verified.

Can politicians object?

Politicians can object to a state's results during the congressional certification on January 6, as several Republicans did after the 2020 election.

In 2021, the House and Senate both voted to reject Republican objections to the Arizona and Pennsylvania results.

After Mr Trump tried to overturn his defeat to Democrat Joe Biden and his supporters stormed the Capitol on January 6, 2021, Congress updated the 1800s-era Electoral Count Act to make it harder to object to results and to more clearly lay out the vice president's ceremonial role, among other changes.

Mr Trump had pressured his vice president, Mike Pence, to object to the results – something the vice president has no legal standing to do.

The newly elected president will be sworn in on January 20.