56% of US voters said that they think Biden and Trump are too old to win the 2024 presidential election. Mandel NGAN/AFP

After attending the Conservative Political Action Conference (CPAC) annual meeting in National Harbor, Maryland, US, Former US President Donald Trump has been criticised for delivering another "lie-filled" speech.

Ahead of the next presidential election, set to take place on 5 November this year, voters have been coming to terms with the fact that the nations largest candidates would become the oldest president in US history by the end of their term.

In a recent report, published by Special Counsel Robert Hur, Democratic Party Leader Joe Biden was described as a "well-meaning, elderly man with a poor memory".

The 81-year-old, who has been US President since the start of 2021, faced questions over whether he was too old to be the nation's leader after he suffered a series of falls on live television last year.

Last month, after it was revealed that Biden's age remains a top concern for voters, the president mocked his age and memory during a speech at a political conference.

"I know I don't look like it, but I have been around for a while," Biden joked.

During his CPAC speech, Trump, 77 years old, impersonated Biden and mocked the president for asking people where he was and falling on stage.

The former president said: "Four years ago I told you that if crooked Joe Biden got to the White House, our borders would be abolished, our middle class would be decimated and our communities would be plagued by chaos and violent crime."

"We were right about everything," he added.

Less than 15 minutes into his speech, Trump said: "If crooked Joe Biden and this thugs win in 2024, the worst is yet to come."

Veering off script, the former US president continued to champion his own "very informative stories" and denied those who have criticised his mental wellbeing.

Almost an hour into his 87-minute speech, Trump said: "They'll say he rambled – he's cognitively impaired... No, it's really the opposite. It's total genius, you know that."

During a speech earlier this year, the Republican Party Leader also told his crowd that, as president, "we will introduce the death penalty" for drug-dealers.

The republicans would introduce the death penalty as a compulsory punishment and an "act of kindness", Trump said, claiming that that the US has "become a drug-infested, crime-ridden nation which is incapable of solving the smallest problem".

According to Paul Quirk, a Professor for Political Science at the University of British Columbia in Canada, voters should recognise how "Biden's age should be less of an issue than Trump's more apparent cognitive decline".

Quirk told Newsweek that Trump's insanity is "displayed in slurred speech and grow, repeated errors in one campaign rally after another".

He has been, if anything, surprisingly effective in policy terms,' the professor added, noting that the special counsel's report that highlighted and mocked Biden's "memory problems" has been "widely disparaged as a partisan hit job".

While voters remain unconvinced about both candidates, a recent ABC News and Ipsos poll found that 59 per cent of Americans said that they think that both Biden and Trump are too old to run for presidency in 2024.

In a webinar last week, S Olshansky, a Professor of Public Health at the University of Illinois at Chicago and a Research Associate at the Center on Aging at the University of Chicago, revealed that, roughly, the presidential candidates both have a 75 per cent chance of living to the end of their second terms in office.

While addressing a American Federation for Aging Research panel, Olsahnsky slammed voters for criticising the presidential candidates for their age.

"I get a phone call every time either one of them stumbles or says something that's off-kilter," the professor said.

The professor added: "They're going 'what's wrong?' I'm going, 'seriously, this happens to virtually all of us'".