Harris’ lead over Trump continues to increase in US national and swing state polls

The United States presidential election will be held on November 5. In analyst Nate Silver’s aggregate of national polls, Democrat Kamala Harris leads Republican Donald Trump by 46.8–43.7 with 3.9% for Robert F. Kennedy Jr. In my previous US politics article on August 5, Harris led Trump by 45.5–44.1.

Joe Biden’s final position before his withdrawal as Democratic candidate on July 21 was a national poll deficit against Trump of 45.2–41.2. By the election, Biden will be almost 82, Trump will be 78 and Harris will be 60.

The US president isn’t elected by the national popular vote, but by the Electoral College, in which each state receives Electoral Votes based mostly on population. Almost all states award their Electoral Votes as winner takes all, and it takes 270 Electoral Votes to win (out of 538 total).

In the states narrowly won by Biden in 2020, Harris leads Trump by 4.1 points in Michigan, 3.8 points in Wisconsin, 2.1 points in Pennsylvania, two points in Nevada and one point in Arizona. Georgia is the only Biden-won state that still has Trump ahead, by 0.5 points. Trump is ahead by 1.1 points in North Carolina, a state he won in 2020.

There has been movement to Harris across all swing states in the past week. If Harris wins all the states she currently leads in, she would win the Electoral College by a 287–251 margin.

Silver’s model gives Harris a 56% chance to win the Electoral College and a 68.5% chance to win the national popular vote. Harris’ Electoral College chances have improved from 50.5% on August 5 and 37% when the Harris vs Trump model was launched on July 29. Trump had a 73% chance to win when his opponent was Biden.

Harris needs at least a two-point win in the national popular vote to be the Electoral College favourite, so the Electoral College is still relatively close. There’s also still plenty of time in which things could go wrong for Harris, or the polls could be understating Trump, as they did in 2020. But currently Harris is the slight favourite to win.

Harris’ net favourability in the FiveThirtyEight tracker of national polls is -4.1, with 48.0% unfavourable and 44.0% favourable, Her net favourablity has surged since Biden’s withdrawal, when it was -16.0. Trump’s net favourability has improved since the mid-July Republican convention, and is now -8.2 (it was -12.0 before the convention).

Trump’s running mate, JD Vance, has a -9.4 net favourable rating, down from -3.3 when he was announced at the Republican convention. Harris’ running mate Tim Walz is at about net +5 favourable. Biden’s net approval is still poor at -16.3.

The Democratic convention will take place from Monday to Thursday next week. Normally, major party presidential candidates are well known to voters by this stage, as they need to win the nominations by winning primaries that are held early in an election year.

In this case, Harris has only been the Democratic candidate for three weeks, and so the Democratic convention is a big opportunity for her to personally appeal to voters. Silver’s model will anticipate a bounce for Harris from the convention, and won’t move in her favour unless her bounce is bigger than expected.

Last week, Harris selected Minnesota Governor Tim Walz as her vice presidential candidate. Media reports suggested the final two candidates for this position were Walz and Pennsylvania Governor Josh Shapiro.

In Silver’s model, Pennsylvania is most likely to be the “tipping point” state. If either Trump or Harris win Pennsylvania, they win the Electoral College over 93% of the time.

The tipping point state is the state that puts the winning candidate over the magic 270 Electoral Votes. It is calculated after the election by ordering all states and their Electoral Votes from biggest Harris to Trump margins, then observing the state and margin that put the winner over 270 Electoral Votes.

The six states that are considered most likely to be won by either Trump or Harris are Nevada (six Electoral Votes), Wisconsin (ten), Arizona (11), Michigan (15), Georgia (16) and Pennsylvania (19). So Pennsylvania is the largest of the swing states.

At the 2022 Pennsylvania gubernatorial election, Shapiro defeated his Republican opponent by a 56.5–41.7 margin in a state that Biden won by just 1.2% in the 2020 presidential election. In a July Pennsylvania poll by Emerson College, Shapiro had a net +18 approval rating, with 49% approving while 31% disapproved.

From the point of view of maximising Harris’ chances of winning Pennsylvania and the election, Shapiro was the better choice. If Harris loses Pennsylvania but gets between 251 and 269 Electoral Votes, so that she would have won with Pennsylvania’s 19, she and Democrats will regret overlooking Shapiro.

In the Electoral College map above that was based on candidate leads in states, if Harris loses Pennsylvania while holding other states she leads in, she loses the Electoral College by 270–268. If she loses Arizona and Nevada but holds Michigan, Wisconsin and Pennsylvania, she wins by 270–268.