WASHINGTON — Hunter Biden has joined meetings with President Joe Biden and his top aides since his father returned to the White House from Camp David on Monday evening, according to four people familiar with the matter.

The president’s son has also been talking to senior White House staff, these people said.

While he is regularly at the White House residence and events, it is unusual for Hunter Biden to be in and around meetings that his father is having with his team, these people said. They said the president’s aides were struck by his presence during their discussions.

Hunter Biden was found guilty last month by a jury in a federal court in Delaware on gun-related charges. He remains under indictment for tax-related felonies, which he has pleaded not guilty. Shortly after the jury found him guilty, Hunter Biden returned to his home in California.

One of the people familiar with the matter said Hunter Biden has been closely advising his father since the family gathered this past weekend at Camp David after Thursday’s debate. This person said Hunter Biden has “popped into” a couple of meetings and phone calls the president has had with some of his advisers.

Another person familiar with the matter said the reaction from some senior White House staff has been, “What the hell is happening?”

Asked to comment, White House spokesman Andrew Bates said: “Hunter came back with the President from their family weekend at Camp David and went with the President straight into speech prep,” referring to Biden’s preparation with aides for remarks on the Supreme Court’s decision on presidential immunity.

Hunter Biden’s presence in and around his father’s meetings comes amid questions about whether Joe Biden should continue his re-election campaign.

NBC News has reported that Hunter Biden is among the president’s immediate family members urging him to stay in the race. He is at the White House this week to celebrate the Fourth of July holiday with the Biden family, two people familiar with his plans said.