WASHINGTON

Ex-President Donald Trump holds a narrow national lead of 0.1%, and remains on top in seven key battleground states by an average of 0.9% with just one week to go before Americans elect the 47th president of the United States.

An average of polling compiled by the RealClearPolitics website shows Trump, the Republican presidential nominee, and Vice President Kamala Harris, a Democratic candidate, in a virtual dead heat nationally ahead of the Nov. 5 election. But Trump leads in key battleground states that will be pivotal to the race's outcome.

Trump's lead is narrowest in Michigan, Wisconsin, Pennsylvania, Nevada and North Carolina where the ex-president is ahead by 0.1%, 0.3%, 0.5%, 0.7% and 0.8% respectively. He leads by 1.5% in Nevada, and 2.3% in Georgia.

Those states are pivotal, because the US does not directly elect its presidents. Instead, the process plays out via the Electoral College where 538 representatives cast their ballots in-line with their state outcomes.

Either candidate needs to secure 270 Electoral College votes to claim victory. Electors are allocated to states based on their population, and most states give all of their electors to whichever candidate wins the state in the general vote.

The winner-take-all model is not adopted in Nebraska and Maine, however, which instead allocate their votes proportionally based on their final outcomes.

Polling conducted in August showed Harris leading Trump in Michigan and Wisconsin, but her margin has vanished in the two months since; so too has her one-time lead in Georgia, Nevada and Pennsylvania.

Should Trump win all seven battleground states that would push him far beyond the threshold for victory. He would win with 312 delegates, leaving Harris with 226.

The fact that the Electoral College ultimately decides the winner of the presidential race has led to the victor losing the popular vote twice in the past 25 years, including Trump's 2016 win when he had nearly three million fewer votes than former Secretary of State Hillary Clinton.

A presidential victor has generally been declared late on election night, but in 2020 it took four days for a winner to be announced due to razor-thin margins in several states, including Georgia where election authorities ordered a hand recount that took days to complete.