LONDON (AP) — US President Joe Biden, in London for the funeral of Queen Elizabeth II, said Sunday his heart went out to the royal family, adding the queen’s death left a “giant hole.”

“It’s a loss that leaves a giant hole and sometimes you think you’ll never overcome it,” said Biden, who often talks in very personal terms about loss following the death of his first wife and young daughter and later, his adult son.

The president and first lady Jill Biden have kept a low profile since landing in the United Kingdom. They traveled to Westminster Hall to pay their respects along with hundreds of thousands of mourners who waited more than 14 hours to walk past the queen’s casket.

Biden and the first lady then went to Lancaster House to sign the condolence book before heading to Buckingham Palace for a reception hosted by King Charles III.

The president spoke briefly after he signed the condolence book. “As I’ve told the king, she’s going to be with him every step of the way,” Biden said. “You were fortunate to have had her for 70 years. We all were.”

He said her reign was about “treating people with dignity.”

“I talk about how my mother and father thought that everyone, no matter who they were … no matter where they’re from, deserved to be treated with dignity,” the president said. “And that’s exactly what she communicated. Just the way she walked by her staff, just the way that she acted.”

Biden wrote in the book that “Queen Elizabeth was admired around the world for her unwavering commitment to service.”

The first lady signed a condolence book for spouses and ambassadors, writing “Queen Elizabeth lived her life for the people. She served with wisdom and grace. We will never forget her warmth, kindness and the conversations we shared.”

The president also said Elizabeth modeled a sense of service.

“There’s something within our capacity to do that can make things, not just the world better, but your neighborhood better, your household better, your workplace better,” he said. “That’s what she communicated to me anyway. It was an honor to meet her, an honor to meet her.”

The president will return to the U.S. on Monday and head to New York for the UN General Assembly, where he’s to gather with Prime Minister Liz Truss, who had just taken over as the queen died.

More than 2,000 people were expected at Westminster Abbey on Monday for the state funeral.