US election: the states Donald Trump and Joe Biden need to win to take the White House

US voters are heading to the polls on Tuesday as the presidential election race nears the finishing line.

The winner of the hard-fought contest between Donald Trump and Joe Biden is unlikely to be declared on the night, owing to the high number of Americans voting via postal ballots as a result of the coronavirus pandemic.

But we could get a good indication of who is going to take the White House if a number of key states are won with a large enough margin. Here are the key battleground states to keep an eye on.

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Electoral maths

In order to win the keys to the Oval Office, Democratic candidate Biden needs to secure 38 electoral votes more than the 232 that Hillary Clinton won in 2016.

The states below have a combined total of 70 electoral votes and were all taken by Trump in 2016. So if Biden can win these four key swing states, he will probably be on the road to beating the incumbent.

Arizona

Four years ago, Trump beat Clinton in this southwestern state by 91,234 ballots, winning 11 key electoral college votes. But in 2020, Arizona appears to be fertile ground for Team Biden, with a poll of likely voters conducted by The New York Times and Siena College giving the former vice-president a six-point lead over the president.

As of April this year, Arizona’s registered voters included 1,370,887 Republicans (34.89%) and 1,277,242 Democrats (32.51%), while the GOP holds a string of key state roles including governor and attorney general.

In the 2018 midterm elections, Democrat Senator Kyrsten Sinema won the so-called Sun Belt state, a seat that had been held by retiring Republican Jeff Flake since 2013. The Republicans had previously held the senior senator position since 1995.

“The average poll overall has Biden up by four points” in Arizona, CNN reports. “So Trump needs a larger than average polling error in a state where there hasn’t been a tradition of polling errors favouring Republicans.”

Florida

The site of one of the most controversial election moments in recent history, during the 2000 battle between George W. Bush and Al Gore, Florida may mark a vital victory for whichever candidate is able to win the Sunshine State.

The adage goes that the further north in Florida you travel, the further south - meaning more conservative - you go politically. Overall, Republicans have often fared well in the state, but the NYT poll has Biden leading by three points.

Trump won Florida in 2016, snatching 29 electoral votes after beating Clinton by 112,911.

Over the weekend, both he and Biden descended on Florida for last-minute rallys, with the Democrat telling supporters: “You hold the power. If Florida goes blue, it's over.”

The president, meanwhile, warned that Biden’s plan is “to deliver punishing lockdowns” to combat the pandemic. “He’s going to lock you down,” Trump told his backers.

Pennsylvania

“At the end of the day, I think if Pennsylvania goes, so will go the country,” the state’s Democratic Attorney General Josh Shapiro recently told Politico. “We are the keystone state.”

The NYT has Biden leading by six points in Pennsylvania, which accounts for 20 electoral college votes - making it a must-win if he is to take the election. Indeed, according to FiveThirtyEight’s presidential forecast, Pennsylvania is “by far the likeliest state to provide either President Trump or Joe Biden with the decisive vote in the electoral college”.

The website’s model says that Trump has an 84% of winning the presidency if he carries the state, while Biden has a 96% of winning if Pennsylvania goes blue.

The state voted Democratic in the six elections prior to 2016. But in the last election, it was one of three so-called “blue wall states” - along with Michigan and Wisconsin - won by Trump.

Wisconsin

In 2008 and 2012, Barack Obama won Wisconsin, but in 2016, Trump took the state by just 23,000 votes. A total of 93,000 black voters in the city of Milwaukee did not cast their ballot four years ago, a phenomena that Obama’s close ally will be hoping is not repeated.

Polling suggests Biden currently has the edge, with the NYT poll giving him a one-point lead over his Republican rival. A separate poll by CNN/SSRS will also give the blue side of the state hope, showing Biden leading by eight points.

With ten electoral college votes, the state is another key building block in a winning coalition. And with Trump only edging to victory in 2016, Biden has reason to be hopeful.

Bonus state: Missouri

The “Missouri bellwether” is an unscientific phenomenon that has seen the state vote for the final winner in all but three US presidential elections from 1904 to 2016.

Missourians voted for the losing candidate in 1956, 2008 and 2012, before backing Trump in 2016.

FiveThirtyEight’s polling average gives Trump a 7.4-point lead in the current contest - leaving Democrats hoping that the state has its sight set wrong for a fourth time.