US President Joe Biden won't attend King Charles III's coronation next month because he is "staunchly proud of his Irish roots,“ according to one editor.

First Lady Jill Biden will instead attend the ceremony on May 6, according to the Washington Post. 

No previous US President has ever attended a royal coronation, with Dwight D. Eisenhower sending a delegation in his place for Queen Elizabeth II's coronation in 1952. 

Russell Myers, the associate editor of the Daily Mail, said King Charles would "break the mold" by inviting world leaders to the coronation next month. 

"King Charles is going to break the mold as it were, inviting foreign leaders – which is quite different to what’s happened before," Myers told Sky News. 

Myers said Biden's "punishing schedule" is partly responsible for his decision to skip the coronation ceremony but said he also declined the invitation due to his Irish roots. 

"Biden is staunchly proud of his Irish roots, his Irish American roots, and so I didn’t think it was a real possibility that he would come," Myers told Sky. 

Right-wing political commentators have criticized Biden's decision to miss the coronation, accusing him of snubbing the monarchy and the "special relationship" that exists between the UK and the US. 

"It seems pretty remiss, and I’m tempted to say more fool him for not coming," Conservative Member of Parliament Bob Seely told the  Daily Telegraph. 

"This is a once-in-a-lifetime event, and you would have thought he should come because he’s a head of state." 

King Charles has said that he wants his coronation to be a shorter ceremony than his mother's, which lasted roughly three hours. 

However, his coronation will still be celebrated with a three-day holiday weekend, including parades, street parties, and picnics.