Five hundred and thirty-seven votes in Florida.
In an election with more than 100 million ballots cast, that’s all it took to make George W Bush president in 2000.
So while the US presidential election is often described as an exercise in appealing to as many voters as possible, candidates will never neglect a niche audience.
Here are five groups – both large and small – that could tip the scales in 2016. CONT.
Tim Swift, BBC News