Pennsylvania holds the key

Democratic candidate Kamala Harris and Republican Donald Trump remain in a tight race in the country's seven battleground states that will determine who will be the next president of the United States of America.

According to the RealClearPolitics Poll Average, Vice President Harris held marginal leads in Wisconsin (+0.4) and Michigan (+1.2). Former president Trump was ahead in Nevada (+1.0), North Carolina (+1.5), Georgia (+1.7), Arizona (+2.7), and Pennsylvania (+0.3).

Trump's lead in Pennsylvania with 0.3 percentage points shows the Republican candidate is gaining momentum in a state which is a must-win battleground for both candidates.

There are 50 states in the US and most of them vote for the same party -- Democratic or Republican -- at every election. That leaves just a handful of states where either candidate could win. At this election, there are seven -- Nevada, North Carolina, Wisconsin, Georgia, Pennsylvania, Michigan and Arizona.

There are 538 electoral college votes up for grabs and the winner will be the candidate that gets 270 or more.

If every state aside from the battlegrounds votes as expected, that would give Vice President Harris 226 electoral votes and Trump 219. The swing states have 93 votes.

Among those seven battlegrounds, Pennsylvania, the most populous and with 19 electoral votes, stands out as the most likely state to determine whether Kamala Harris or Donald Trump is the next president.

Michigan, Pennsylvania and Wisconsin had served as a "blue wall" for Democratic candidates for a generation. But, in 2016, Trump narrowly carried all three, fueling his upset victory over Democrat Hillary Clinton.

Four years later, Joe Biden won the presidency after reclaiming Michigan, Wisconsin and Pennsylvania for Democrats, while also notching surprising victories in Georgia and Arizona, two states that had historically voted Republican.

WHY IS PENNSYLVANIA SO IMPORTANT?

The simplest answer is that the state has 19 electoral votes, more than any other battleground. According to some projections, the candidate who wins Pennsylvania has upwards of a 90 percent chance of winning the White House.

If Harris loses Pennsylvania, she would need to carry either North Carolina or Georgia -- two states that have voted Democratic a total of three times in the last four decades – to have any chance of prevailing.

Conversely, if Trump loses Pennsylvania, he would need to win either Wisconsin or Michigan, which have only voted for a Republican once since the 1980s - for Trump eight years ago.

Both campaigns have treated Pennsylvania as the most important state, with Harris and Trump spending more time there than in any other. The campaigns and their allies had spent $279.3 million in broadcast advertising in Pennsylvania through Oct 7, more than $75 million ahead of second-place Michigan, according to the tracking firm AdImpact.

WHY IS A NEBRASKA DISTRICT DRAWING SO MUCH ATTENTION?

Forty-eight states award their electoral votes on a winner-take-all basis, but two states, Nebraska and Maine, allocate one electoral vote to the winner in each congressional district. In 2020, Biden won one of Nebraska's five votes, while Trump took one of Maine's four votes.

The single electoral vote in Nebraska's 2nd Congressional District, centred on Omaha, is seen as competitive, though independent analysts favour Harris to win it. Both parties have spent millions of dollars airing ads in the Omaha market.

That lone vote could be crucial. If Harris wins Michigan, Pennsylvania and Wisconsin while Trump takes the other four battlegrounds – an entirely plausible outcome – Nebraska's 2nd District would determine whether the election ends in a tie or whether Harris prevails.