The contest to be president of the US takes place across 50 states (and the District of Columbia) but it is generally won or lost in a handful of key battlegrounds.
The road to the White House this year runs through seven swing states: Arizona, Georgia, Michigan, Nevada, North Carolina, Pennsylvania and Wisconsin.
With so much riding on perhaps as few as hundreds of thousands of voters in states like these, let's look at how the polls in those places are looking.
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We'll break down each state by how many Electoral College votes it awards (a candidate needs a total of 270 to win the presidency), how it voted in 2020 and what the latest polls are looking like.
A note on the polls - a Democrat nominee to replace Joe Biden has not yet been chosen, and the polls mentioned below were conducted before the president announced his exit from the race.
Arizona - 11 Electoral College votes - voted Democrat in 2020
Once considered a Republican stronghold, changing demographics have seen Arizona increasingly return Democrat politicians in recent years.
The shift in voting patterns culminated in Joe Biden winning the state in 2020 - only the second Democrat presidential candidate in seven decades to do so.
However, recent polling has suggested that Donald Trump could be ahead in the Grand Canyon state.
One poll conducted 16-18 July had Mr Trump (44%) a few points ahead of Mr Biden (40%).
Another, conducted 15-16 July had Mr Trump (49%) again ahead of Mr Biden (44%). It also had him ahead of Kamala Harris by 48% to 42%.
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Georgia - 16 Electoral College votes - voted Democrat in 2020
One of the biggest wins for Mr Biden in 2020, rapid growth in the Atlanta suburbs saw him become the first Democratic presidential nominee to win there in nearly three decades.
It was tight - he won by less than 13,000 votes - but the win was boosted by the Democrats taking both Senate seats in the state as well.
A poll conducted 16-18 July had Mr Trump (45%) ahead of Mr Biden (40%) in Georgia.
Another, conducted 15-16 July had Mr Trump (47%) leading Mr Biden (44%). A hypothetical matchup between Mr Trump (47%) and Mrs Harris (37%) also suggested a lead for the Republican.
Michigan - 15 Electoral College votes - voted Democrat in 2020
A part of the key 'rust belt' group of states, Michigan is the home state of star Democrat governor Gretchen Whitmer.
The Great Lakes state was won by Mr Trump in 2016, the first Republican to do so for many years, but won by Mr Biden in 2020.
A poll conducted 17-18 had Mr Trump (49%) ahead of Mr Biden (46%). He was also ahead in a hypothetical matchup with Mrs Harris (46% to 41%).
However, in a hypothetical showdown with Mrs Whitmer, Mr Trump (45%) was a point behind the state governor (46%).
Nevada - six Electoral College votes - voted Democrat in 2020
Most of Nevada is rural, with the population predominantly concentrated in just two counties.
A poll conducted 16-18 July had a lead for Mr Trump (44%) over Mr Biden (41%).
Another poll put him several points above Mrs Harris (50% to 40%).
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North Carolina - 16 Electoral College votes - voted Republican in 2020
North Carolina narrowly voted for Mr Trump over Mr Biden in 2020, with less than 100,000 votes in the contest in the state, whose population is more than 10 million.
It was one of the upsets of the 2020 election, with Mr Biden previously favoured to win the Tar Heel state.
A poll conducted 16-18 July had Mr Trump (45%) ahead of Mr Biden (39%) in the rematch.
Another, conducted 15-16 July had Mr Trump (47%) ahead of Mr Biden (38%).
Pennsylvania - 19 Electoral College votes - voted Democrat in 2020
Mr Biden's home state is a crucial battleground in the 2024 election, particularly given the substantial amount of Electoral College votes it assigns.
The populous state - part of the Rust Belt - is home to large cities including Pittsburgh and Philadelphia.
It's also home to rising Democrat star Josh Shapiro, the state governor and a key figure in the party.
A poll conducted 16-18 July had Mr Trump (45%) ahead of Mr Biden (41%). Another, conducted 17-18 July, put Mr Trump ahead of Mr Biden by 46% to 42%.
Meanwhile, in polls conducted 17-18 July, Mr Shapiro (47%) led Mr Trump (43%), while the Republican was ahead of Mrs Harris 45% to 43%.
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Wisconsin - 10 Electoral College votes - voted Democrat in 2020
A close election last time round, Mr Biden won Wisconsin by around 20,000 votes. And it could be tight again.
It's also one of the best predictors of the nationwide winner - Wisconsin has backed the winning candidate every year since 2008.
A poll conducted 16-18 July had Mr Biden (42%) and Mr Trump (42%) tied for the lead in the battleground state, while another conducted 15-17 July had Mr Trump (46%) in the lead over Mr Biden (43%).
