J oe Biden must be senile. Did you see that video? Couldn’t even remember the place or the date or the year he was talking about. Donald Trump, too. He kept inventing words and then seemed to freeze. And what about Nancy Pelosi? Sounded like she was drunk. Wish a family member would step in and have a word. Sad, really.

This, at least, is the impression that may have been formed by anyone who had spent much time on social media in recent months, as the 2020 election cycle gathers heat and intensity.

A succession of videos, some more crude and obviously fake than others, have done the rounds, bringing whispers and accusations into the mainstream, and further raising legitimate questions about America’s three most significant politicians, all in their seventies. How they perform over the next 14 months will greatly determine the course of the nation.

If this toxic campaign of attack ads appears shocking, what is even more staggering is that there is little new about it. Dirty politics has been a constant presence in presidential campaigns, and one that has frequently determined the course of an election.

At a time when political discourse and media coverage is dominated by the falsehoods and brash attacks repeatedly fired off by Trump, it may come as a surprise to recall that in 2000, supporters of George W Bush, now championed by some as a “respectable” example of a Republican president, spread false rumours that his primary opponent, John McCain, had fathered an “illegitimate” child with an African American woman.

The Democrat challengers to Trump in 2020 Show all 25 1 /25 The Democrat challengers to Trump in 2020 The Democrat challengers to Trump in 2020 Bernie Sanders The Vermont senator has launched a second bid for president after losing out to Hilary Clinton in the 2016 Democratic primaries. He is running on a similar platform of democratic socialist reform Getty The Democrat challengers to Trump in 2020 Joe Biden The former vice president recently faced scrutiny for inappropriate touching of women, but was thought to deal with the criticism well and has since maintained a front runner status in national polling EPA The Democrat challengers to Trump in 2020 Elizabeth Warren The Massachusetts senator is a progressive Democrat, and a major supporter of regulating Wall Street Reuters The Democrat challengers to Trump in 2020 Amy Klobuchar Klobuchar is a Minnesota senator who earned praise for her contribution to the Brett Kavanaugh hearings Getty The Democrat challengers to Trump in 2020 Michael Bloomberg Michael Bloomberg, a late addition to the 2020 race, announced his candidacy after months of speculation in November. He has launched a massive ad-buying campaign and issued an apology for the controversial "stop and frisk" programme that adversely impacted minority communities in New York City when he was mayor Getty Images The Democrat challengers to Trump in 2020 Tulsi Gabbard The Hawaii congresswoman announced her candidacy in January, but has faced tough questions on her past comments on LGBT+ rights and her stance on Syrian President Bashar al-Assad Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Pete Buttigieg The centrist Indiana mayor and war veteran would be the first openly LGBT+ president in American history Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Deval Patrick The former Massachusetts governor launched a late 2020 candidacy and received very little reception. With just a few short months until the first voters flock to the polls, the former governor is running as a centrist and believes he can unite the party's various voting blocs AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Beto O'Rourke The former Texas congressman formally launched his bid for the presidency in March. He ran on a progressive platform, stating that the US is driven by "gross differences in opportunity and outcome" AP The Democrat challengers to Trump in 2020 DROPPED OUT: Kamala Harris The former California attorney general was introduced to the national stage during Jeff Sessions’ testimony. She has endorsed Medicare-for-all and proposed a major tax-credit for the middle class AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Bill De Blasio The New York mayor announced his bid on 16 May 2019. He emerged in 2013 as a leading voice in the left wing of his party but struggled to build a national profile and has suffered a number of political setbacks in his time as mayor AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Steve Bullock The Montana governor announced his bid on 14 May. He stated "We need to defeat Donald Trump in 2020 and defeat the corrupt system that lets campaign money drown out the people's voice, so we can finally make good on the promise of a fair shot for everyone." He also highlighted the fact that he won the governor's seat in a red [Republican] state Reuters The Democrat challengers to Trump in 2020 DROPPED OUT: Cory Booker The New Jersey Senator has focused on restoring kindness and civility in American politics throughout his campaign, though he has failed to secure the same level of support and fundraising as several other senators running for the White House in 2020 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Wayne Messam Mayor of the city of Miramar in the Miami metropolitan area, Wayne Messam said he intended to run on a progressive platform against the "broken" federal government. He favours gun regulations and was a signatory to a letter from some 400 mayors condemning President Trump's withdrawal from the Paris Climate Accord Vice News The Democrat challengers to Trump in 2020 DROPPED OUT: Kirsten Gillibrand The New York Senator formally announced her presidential bid in January, saying that “healthcare should be a right, not a privilege” Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Delaney The Maryland congressman was the first to launch his bid for presidency, making the announcement in 2017 AP The Democrat challengers to Trump in 2020 DROPPED OUT: Andrew Yang The entrepreneur announced his presidential candidacy by pledging that he would introduce a universal basic income of $1,000 a month to every American over the age of 18 Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Julian Castro The former San Antonio mayor announced his candidacy in January and said that his running has a “special meaning” for the Latino community in the US Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Marianne Williamson The author and spiritual adviser has announced her intention to run for president. She had previously run for congress as an independent in 2014 but was unsuccessful Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Eric Swalwell One of the younger candidates, Swalwell has served on multiple committees in the House of Representatives. He intended to make gun control central to his campaign but dropped out after his team said it was clear there was no path to victory Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Seth Moulton A Massachusetts congressman, Moulton is a former US soldier who is best known for trying to stop Nancy Pelosi from becoming speaker of the house. He dropped out of the race after not polling well in key states Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Jay Inslee Inslee has been governor of Washington since 2013. His bid was centred around climate change AFP/Getty The Democrat challengers to Trump in 2020 DROPPED OUT: John Hickenlooper The former governor of Colorado aimed to sell himself as an effective leader who was open to compromise, but failed to make a splash on the national stage Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tim Ryan Ohio representative Tim Ryan ran on a campaign that hinged on his working class roots, though his messaging did not appear to resonate with voters Getty The Democrat challengers to Trump in 2020 DROPPED OUT: Tom Steyer Democratic presidential hopeful billionaire and philanthropist Tom Steyer is a longtime Democratic donor AFP/Getty

The smears were all the more painful because they were given fuel by the fact McCain and his wife, Cindy, had adopted a little girl, Bridget, from Bangladesh. A phone poll, seemingly designed to spread the rumour rather than obtain actual opinions, asked voters: “Would you be more or less likely to vote for John McCain, if you knew he had fathered an illegitimate black child?”

McCain, whose “Maverick” campaign had come to South Carolina having just won a surprise primary victory in New Hampshire, said it amounted to libel. “There wasn’t a damn thing I could do about the subterranean assaults on my reputation except to act in a way that contradicted their libel,” he wrote in his memoir Worth the Fighting For: The Education of an American Maverick. The Bush campaign denied any involvement, but he won South Carolina, captured the Republican nomination, defeated Democrat Al Gore by the narrowest of margins – 537 votes in Florida – and entered the White House.

The standard operating procedure of a campaign is to start positively, but also to go negative when they believe it will not boomerang backwards Elaine Kamarck, Brookings Institution

Bush’s father also had a hand in dirty politics. In his 1988 contest against Michael Dukakis, the Bush campaign used the now notorious Willie Horton advert to link the Democrat to an African American prisoner let out under a furlough programme in Massachusetts, where Dukakis was governor, and who then killed a woman. Dukakis had been leading in the polls, but the racially charged campaign badly damaged him, and Republicans were able to pull off the rare feat of holding the presidency for three for successive terms.

This sort of thing has been going on since America’s very first elections. Historian Rick Shenkman, author of Presidential Ambition: Gaining Power at Any Cost, has detailed how dirty tricks date back to the beginning of the republic.

“Our first two elections were pretty clean, but after that they became dirty,” he tells The Independent. “Even [America’s first president] George Washington complained he had to endure more attacks than Emperor Nero did.”

At a time, when the media was even more partisan than it was now, the nation’s third president, Thomas Jefferson, fought off accusations he had fathered children with one of his slaves. Jefferson was able to defeat incumbent John Adams, and 200 years later, his long relationship with Sally Hemings, a member of the staff at his Monticello plantation, was finally acknowledged by historians. The couple had six children.

Trump insults Biden ahead of crucial campaigning in Iowa: 'I think he’s the weakest mentally'

Experts say the practice of dirty politics has continued, all the way down through Nixon 1972’s campaign against George McGovern and into our era, because it frequently works.

“They have very often been effective,” says Elaine Kamarck, director of the centre for effective public management at the Brookings Institution and a scholar at Harvard University. “The standard operating procedure of a campaign is to start positively, but also to go negative when they believe it will not boomerang backwards.”

Kamarck says the internet has increased the amount of messaging and disinformation that can be spread, and the way it can be targeted at certain groups. And while a 2002 “Stand by your Ad” law, also known as the McCain-Feingold Act, requires any adverts from a campaign or party on television or radio to be identified as such, usually by the candidate saying “I approve this message”, there is no such demand for the online world, which has emerged as an increasingly important battleground.

This means voters have less information as to whether an advert claiming a certain candidate hates Muslims is an official message, the work of one of the many massively funded political action committees (PACs), or disinformation spread by Russia.

George HW Bush sweated in his first debate against Michael Dukakis but went on to beat him with help of a notorious attack advert (AP)

At the same time, social media giants are struggling to determine how best to monitor and regulate such content. The most notorious of the doctored videos of Pelosi was taken down by YouTube, which said it violated its standards, but continued to be hosted by Twitter and Facebook, even though the latter tech firm deemed it false. In the end, millions watched the Democratic speaker of the House of Representatives apparently slurring her words in a speech.

Caroline Orr, a behavioural scientist at Virginia Commonwealth University, says negative campaigning and dirty tricks play to the emotions.

“It’s intended to arouse emotions so people don’t evaluate the information as critically as they might, and just internalise it,” she says.

“It’s successful a lot of the time because it feeds into people’s pre-existing beliefs. If somebody is sceptical about immigration and they see an inflammatory ad on that subject, they are more likely to believe it without measuring it. Time and time again, emotional appeal has proven to be the most effective.”

It’s pretty hard to shock people these days, whether it is politics or anything else. You’ve got to come up with something really good to make it stick David Mark, Washington Examiner

She said as more people relied on social media for their news, they became increasingly isolated from other view points “because the algorithms learn what you want to read”.

One of the many ways Trump has broken conventions as president is to spearhead attack adverts himself. Several times, Trump, 73, has claimed that 76-year-old Biden has lost it.

“Look, Joe is not playing with a full deck,” Trump told reporters this summer, after the former vice president made one of a succession of gaffes while campaigning, telling a crowd “poor kids are just as bright, just as talented, as white kids”.

Trump, along with his lawyer and surrogate Rudy Giuliani, also retweeted one of the several doctored clips of Pelosi, and the president annotated his post with the words “PELOSI STAMMERS THROUGH NEWS CONFERENCE”.

Even though there is large eco-system on the left that creates attack adverts about Trump, even if it is not as big as the one on the right, Biden has yet to resort to personal insults towards the president.

He and his campaign insist he remains as sharp as he ever was, despite doubts about his age among some supporters. He remains the Democrats’ frontrunner by some measure, leading his rivals by between four to eight points depending on which poll you examine.

David Mark, a senior journalist with the Washington Examiner and author of Going Dirty: The Art of Negative Campaigning, says another thing Trump has done is to raise the bar of what is shocking.

Among the early advisers to the Trump campaign was veteran operative Roger Stone who has long relished his reputation as a “political ratf***er”. In January, Stone pleaded not guilty to charges of witness tampering brought by Robert Mueller as part of his probe into Russia’s alleged interference in the 2016 election and possible collusion with the Trump campaign.

“Oh absolutely, it’s going to get more intense,” says Mark, looking to the coming months. If Biden becomes the Democrats’ nominee, he says, we should expect plenty of attacks about his hair, given that he appears to have more now than he did in the 1980s when he was a nearly-bald senator.

“Even though it’s going to be nastier than ever, I am not sure it’s going to have as as much impact because people are used to this stuff,” he says.