WATCH: Biden again refers to VP as ‘President Harris’ during White House’s Stanley Cup celebration

President Biden referred to Vice President Kamala Harris as 'President Harris' during the White House's Stanley Cup celebration on Monday.

'President Harris is here to make sure we do this the right way,' Biden, 80, said in an apparent joke just moments after taking the stage to honor the Las Vegas Golden Knights, who won the Stanley Cup in June.

The gaffe marks the latest instance in which Biden has mistakenly referred to Harris as the 'president,' which has happened on at least six prior occasions. 

On one such occasion in Oct. 2022, Biden called Harris 'a great president' while wishing her a happy birthday during a White House event. 'Happy Birthday to a great president, we know your mom is always with you,' Biden said.

He called her 'President Harris'  during remarks in South Carolina in December 2021, and did so at another event earlier that year in January. In March 2022, he also mistakenly called Harris the 'first lady' while talking to reporters.

Biden, who turns 81 on Nov. 20, is the oldest person to ever serve as president. If elected to a second term, he would be 82 on inauguration day, and 86 upon leaving office.

Harris, 59, has frequently defended Biden from concerns over his age, including from within their own party. Last month, she told '60 Minutes' that 'Joe Biden is very much alive and running for re-election.'