Biden jests about wishing his ancestor had been among the group that overthrew oppressive mine bosses.

President Biden quipped that he was initially "disappointed" to discover that his great-grandfather was not associated with a violent organization responsible for murdering prejudiced mine supervisors.

During a rally in Pittsburgh on Monday, the president discussed his ancestor, Edward Francis Blewitt, while supporting Democratic presidential nominee Vice President Kamala Harris.

"Biden recounted to the audience how his great-grandfather was the second Catholic elected to the state Senate in Pennsylvania at the time, and how opponents had labeled him a "Molly Maguire" during the 1906 election."

"The Molly Maguires were a group of English-owned coal mines who would kill foremen who took advantage of individual workers. They would then bring the bodies of their victims to the foreman's family's doorstep. This was not a joke, as Biden emphasized."

The president shared a story about his maternal ancestor, an anecdote he had used during his campaign with former President Barack Obama, and Harris listened attentively.

"Although a bit rough around the edges, I must confess that my great-grandfather was falsely accused of being a Molly Maguire, which left us feeling utterly disappointed," Biden said, quickly adding, "It was all just a joke."

In 1907, Blewitt became the second Catholic individual to be elected to the Pennsylvania Senate, succeeding William McSherry, who served from 1813-1817.

Biden's visit to Pittsburgh signifies the end of a week-long low-key vacation in Rehoboth Beach, Delaware.

Biden cleared his work schedule for a multi-week holiday, which was immediately followed by a six-day getaway to Democratic Party donor Joe Kiani's California ranch estate.

The poor showing of Biden against Trump in their June debate intensified worries among Americans about Biden's ability to handle another term as president due to his age.

The growing number of calls from top Democratic Party allies and elected officials urged Biden to withdraw from the presidential race, which he did on July 21, followed by an endorsement of Harris.

While most recent national polls indicate a slight lead for Harris over Trump, it's important to note that the presidential election is not a national popular vote contest. Instead, it's a battle for individual states and their electoral votes.

Planet Chronicle Digital's Paul Steinhauser contributed to this report.