In the US Electoral College, a candidate needs at least 270 out of 538 Electoral votes to win the election.

Each state is allocated a certain number of Electoral votes based on its population. Some states consistently favour one party, while “battleground” or “swing states” can shift, making them crucial in deciding the election.

This election features seven battleground states, totalling 93 electoral votes: Pennsylvania (19), Georgia (16), North Carolina (16), Michigan (15), Arizona (11), Wisconsin (10), and Nevada (6).

How can Kamala Harris win?

Harris is projected to secure at least 226 Electoral votes from 19 states and the District of Columbia, with major contributions from California (54), New York (28) and Illinois (19).

To reach 270 Electoral votes, Harris will need at least 44 of the 93 battleground votes.

The easiest path for her would be to win Pennsylvania (19), Georgia (16) and North Carolina (16), securing 51 Electoral votes and a Harris presidency. However, at the moment, she is trailing Trump in all three, according to the FiveThirtyEight average of polls – Pennsylvania only very marginally, and Georgia and North Carolina by slightly bigger margins.

Mathematically, Democrats have 10 possible ways in which Harris could get to 270 Electoral College votes by winning just three of the seven battleground states, and another 10 ways by winning four states. Winning five or more battleground states would secure the presidency for either candidate.

Here’s the combination of three or four swing states Harris would need to win to get to 270:

How can Donald Trump win?

Republicans are projected to secure at least 219 Electoral votes from 24 states nationwide, with major contributions from Texas (40), Florida (30) and Ohio (17).

To reach 270 Electoral votes, Trump will need at least 51 of the 93 battleground votes.

Just like the Democrats, the easiest path for him is to win Pennsylvania (19), Georgia (16) and North Carolina (16), securing 51 Electoral votes and bringing the Republicans up to exactly 270 Electoral votes to win the presidency. He currently leads in all three states, per poll trackers.

If Republicans do not win all of those three states, then they must win at least four out of the seven battleground states to secure the presidency. Mathematically, Republicans have 20 four-state winning combinations.

Which paths are likeliest for Harris and Trump?

According to analysts, the race remains extremely close, and the dynamics could shift, but Pennsylvania, which holds 19 Electoral votes, is a critical battleground state.

“They both need Pennsylvania,” said Raymond J La Raja, professor of political science at the University of Massachusetts Amherst.

Pennsylvania’s importance in the election has led candidates to invest heavily in campaigning and advertising.

The Harris and Trump campaigns reportedly spent $360m on TV, digital, and radio advertisements in this state alone.

If Harris wins, “one of her potential paths to victory runs through Pennsylvania and Wisconsin,” La Raja explained.

According to FiveThirtyEight’s National Polls tracker, Harris holds a narrow lead of 0.60 points in Wisconsin, while Trump leads in Pennsylvania by 0.70 points.

“If Harris is going to win narrowly, she needs to secure what we call the ‘blue wall’ – Pennsylvania and Wisconsin,” La Raja explained.

The “blue wall” refers to a bloc of states that consistently voted Democratic in presidential elections until 2016, when Trump flipped three: Pennsylvania, Michigan and Wisconsin. Together, these states represent a crucial 44 Electoral votes in the 2024 election.

In Michigan, Harris currently leads by a slim margin of 0.80 points, according to FiveThirtyEight’s National Polls tracker.

“If she wins those states but loses other swing states, she could still narrowly clinch the election with just over 270 Electoral votes,” La Raja added.

For Trump, a win in North Carolina, Georgia and Arizona – states where his lead has been steady at more than 1 percentage point for several days – coupled with a win in Pennsylvania would represent a clear path to victory.

“There’s also another scenario for Trump,” La Raja said. “If he wins North Carolina, Georgia, Arizona, and Nevada, along with Wisconsin, even if Harris wins Pennsylvania, he could still pull off a narrow victory.”

However, experts caution that the race remains tied and highly unpredictable.

What happens if Harris and Trump end in a tie?

There are three scenarios in which Harris and Trump could both reach 269 Electoral votes.

This could occur if there are no surprises, with Harris and Trump securing their 226 and 219 Electoral votes respectively, and the following outcomes in the battleground states:

Scenario 1:

• Democrats win:
  Georgia (16), Arizona (11), Wisconsin (10) and Nevada (6)
• Republicans win:
  Pennsylvania (19), North Carolina (16) and Michigan (15)

Scenario 2:

• Democrats win:
  Georgia (16) North Carolina (16) and Arizona (11)
• Republicans win:
  Pennsylvania (19), Michigan (15), Wisconsin (10) and Nevada (6)

Scenario 3:

• Democrats win:
  North Carolina (16), Arizona (11), Wisconsin (10) and Nevada (6)
• Republicans win:
  Pennsylvania (19), Georgia (16) and Michigan (15)

If any of these outcomes occur, then a contingent election takes place in which the US House of Representatives decides the winner.

Each state’s delegation in the House would cast one vote, and a candidate must receive a majority (26 out of 50) of the state delegation votes to win.

The US Senate would then choose the vice president with each senator casting one vote and a simple majority (51 votes) required to win.

The graphic below highlights the winning combinations for each candidate.