Joe Biden reportedly confused Saddam Hussein and Osama bin Laden while defending his foreign policy record during a rally in Iowa.

The former Vice President, 77, made the gaffe while responding to a voter who asked whether he could be trusted on foreign policy, given that he voted to authorize the use of military force in Iraq in 2002 and cautioned President Obama against conducting the successful raid on Osama bin Laden's compound in 2011.

According to Politico, Biden at one point scrambled the two separate incidents in his 'lengthy response' by mixing up the former Iraqi president with the one-time leader of al-Qaeda.

The incident occurred last Saturday at a rally in Des Moines - three days before he mixed up Iran and Iraq while speaking at an event in New York.

Biden is trying to tout his foreign policy experience and present himself as a steady hand following President Trump's strike on Qassem Soleimani and increasing tensions between the US and Iran.

But Biden has been attacked over his record by Democratic rival Bernie Sanders who is surging ahead of the former VP in a new poll of Iowa voters.

On Monday, Sanders blasted Biden during an interview on CNN, stating: 'Joe Biden voted and helped lead the effort for the war in Iraq, the most dangerous foreign policy blunder in the modern history of this country.'

Joe Biden reportedly confused Saddam Hussein and Osama bin Laden while defending his foreign policy record during a rally in Des Moines, Iowa last weekend. He is pictured at the event

According to Politico, Biden at one point mixed up the former Iraqi president (left) with the one-time leader of al-Qaeda (right)

Meanwhile, in a separate interview with The Washington Post earlier this week, Sanders blasted Biden again, stating: 'People are tired of the traditional types of campaigns in which candidates like Joe are running to wealthy people's homes and raising large sums of money.'

He added: 'It's just a lot of baggage that Joe takes into a campaign, which isn't going to create energy and excitement. He brings into this campaign a record which is so weak that it just cannot create the kind of excitement and energy that is going to be needed to defeat Donald Trump.'

The attacks on Biden appear to be working for Sanders - who famously voted against intervention in Iraq - as he is now the frontrunner in Iowa, according to a new CNN/ Des Moines register poll released Friday.

Sanders has jumped five points from a previous poll conducted in November, and now commands 20% of the new poll's vote share.

The attacks on Biden appear to be working for Sanders who is now the frontrunner in Iowa, according to a new CNN/ Des Moines register poll released Friday

Massachusetts Senator Elizabeth Warrren is holding steady with 17%, while former frontrunner Pete Buttigieg has seen his support slip in the state, dropping a whopping nine points in the two months since the November poll.

He now commands 16% of the share - but is still ahead of Biden, who is languishing in fourth place with 15%.

Meanwhile, Biden's wife, Dr Jill Biden, doesn't approve of Sander's stinging new attacks on her husband - hitting back in a CNN interview on Saturday.

The former Second Lady stated: 'Joe has been under attack because he's doing so well. And I don't like it that Democrats attack other Democrats. We're in this race against Donald Trump. We're not against any of the other Democrats.'

As for Sanders' claims that her husband has baggage, Jill shot back: 'That's ridiculous!'