While election almost certain to be decided by swing states, pollsters explain why growth in national polls is meaningfulKamala Harris has stretched her lead over Donald Trump in the US presidential election race, the latest polling averages show, even while the two candidates appear to be running neck-and-neck in most battleground states.The Guardian’s newest poll tracker, based on a range of surveys conducted across a 10-day period, shows the vice-president and Democratic nominee at 48.2%, compared with 44.4% for Trump, the Republican candidate and former president – giving Harris a 3.6-point advantage. Continue reading...