American citizens in London could assist influence important states that could determine the election's outcome because Donald Trump and Kamala Harris are in such a close fight for the US presidency, according to top experts.US voters abroad can "punch above their weight" because, despite their relatively small numbers, they can still have an impact on the outcome in swing states like Georgia, Wisconsin, Pennsylvania, Michigan, Arizona, Nevada, and North Carolina, according to John Scardino, UK vice chair of Democrats Abroad.Because so many swing states are so close, surveys anticipate that the matchup between Trump and Ms. Harris will be tight.Mr. Scardino told BBC London Politics, "Democrats Abroad has been working our asses off to go out and find every American that we possibly can in the UK." "We don't have many voters, but the impact is enormous, so overseas voters kind of punch above their weight." “So out of five million votes overall that were cast in the state, he won by a margin of just 11,000.

“These are small numbers that have this huge impact.”

An estimated 2.8 million US citizens of voting age live abroad, mainly in Canada and Britain.

In London, there are believed to be more than 100,000 US citizens.

Greg Swenson, chairman of Republicans Overseas UK, agrees that Americans abroad may be influential in this election.

“Americans, or Republicans, living abroad was never a real focus,” he said.

“When everybody looked at the maths from 2020..and realized every vote counts, so let’s go get that.”

He added: “We try and concentrate where there are likely Republican voters.

“So, we are not knocking on doors in Islington.

“But we are going to the NFL games, because that is heavily Republican market, then of course the military bases where military personnel vote remarkably weighted towards Republican.

“So, it’s a pretty easy target for us to reach.”

Some 240 million people are eligible to vote in the US presidential election.

Each state has an allocated number of the 538 electoral college votes, partly based on population.

To win the election, a candidate needs to gain 270.

In reality the contest is expected to come down to around seven key states as the others tend to firmly go Democrat or Republican.

So, despite America’s huge size, a few million, if not less, swing voters are set to decide who succeeds Joe Biden in the White House.

Overseas US voters tend to have a low turnout rate, but given the polarised politics of America and the closeness of the election more may be encouraged to take part.

With the result expected to be so close, a series of legal battles are expected, with some having already been launched.

“From what I understand, Republicans in many states have filed over 100 lawsuits already, even before the election day has come,” said Mr Scardino.

Mr Swenson added: “Yes, they (Republicans) have got lawyers, they have got 1,000 lawyers set to file suit if there is any last minute changes.

“Better to be in the courts, I think we can agree on this, and be pro-active about it and make sure it’s settled before the election than have any kind of violence or street activity afterwards.”