President Biden has been “losing focus” during discussions at this week’s G7 summit in Italy, with one diplomatic insider saying the commander-in-chief is “the worst he has ever been.”

Another attendee from a non-US delegation told the Sun Friday that the 81-year-old’s public missteps on the first day of the gathering were “embarrassing.”

Biden has joined the leaders of the world’s wealthiest democracies — including Italian Prime Minister Giorgia Meloni and British Prime Minister Rishi Sunak — for the annual meeting to discuss their nations’ economic and security priorities.

However, the president has stolen the spotlight with a series of bizarre actions, including giving Meloni an awkward salute upon greeting her Thursday and wandering away from his fellow leaders during a skydiving demonstration, forcing the host prime minister to chaperone him back to the group.

Biden apparently got off on the wrong foot with Meloni before the summit even began Thursday morning, keeping the Italian prime minister waiting 20 minutes before arriving, according to public broadcaster RAI.

When the president did appear, Meloni reportedly chided him in an apparent attempt at humor, telling Biden: “You shouldn’t leave a woman waiting like this.”

The Sun also reported that Biden had shown moments of clarity while discussing urgent matters with the leaders of Canada, France, Germany, Italy, Japan, the UK and the European Union.

That is in line with The Post’s understanding from White House staffers that Biden, who would be 86 years old if he completes a full second term in January 2029, has at points lost his focus in private conversations.

White House senior deputy press secretary Andrew Bates described the Sun report as “lies” Friday and touted Biden’s “successful leadership overseas advancing our national security.”

Bates also insisted that The Post and other outlets had reported on a distorted version of the video of Biden walking away from the skydiving demonstration, saying the president was giving “a thumbs up” and saying “congratulations” to another skydiver just out of the video’s frame.

However, Sunak told reporters Friday that the choreography of the ceremony called for Biden to join his fellow leaders.

“He just went over to kind of talk to all of them individually and Georgia [Meloni] was saying, ‘Don’t worry, they’re all coming to [us],’” the British prime minister said.

“We were meant to line up so they could come and then shake all our hands.”

Sunak also defended the American president, saying Biden was “all right” and was “being very polite” to the military members who took part in the demonstration.

Biden also skipped a dinner held for the G7 leaders at a luxury hotel in southern Italy later Thursday evening.

“There’s going to be a lot of meetings happening, a lot of sessions, as you know,” White House press secretary Karine Jean-Pierre told reporters Wednesday in excusing Biden’s absence. “And so, the President is certainly going to be engaged for the — the two days — or two — two — two and a half days that he is in Italy at the G7. So, I wouldn’t read too much into him not going to one dinner.”

The summit has been marked by the US signing a 10-year security agreement with Ukraine and the alliance agreeing to lend another $50 billion to Kyiv in its war effort against Russia.

Ukrainian President Volodymyr Zelensky had requested the assistance while attending the summit, and later joined Biden for a press conference to declare their joint opposition to Russian aggression.

Biden’s mental fitness is increasingly worrying to Democratic lawmakers and aides, a bombshell report from the Wall Street Journal said last week, with the president frequently caught reading off cheat sheets and resting his eyes in meetings.

“You couldn’t be there and not feel uncomfortable,” one source who was in discussions earlier this year over a $95 billion national security package with military aid for Ukraine told the outlet.

A shocking 86% of voters — including 73% of Democrats — believe Biden is too old to finish a second term, an ABC News/Ipsos poll found in February.

First lady Jill Biden in March scoffed at the notion — floated by then-Republican presidential candidate Nikki Haley — of politicians over the age of 75 being forced to take mental competency tests, calling it “ridiculous.”

Biden will square off with former President Donald Trump in their first presidential debate of the cycle June 27 on CNN.

Half of US voters expect the incumbent to forget where he is at some point during the verbal battle, and a third anticipate he will wander away offstage, a JL Partners poll released Thursday shows.

“From Italy to the United Kingdom to New York, millions of people around the world woke up to headlines about Crooked Joe Biden’s cognitive decline on full display at the G7 Summit,” Trump campaign spokesperson Karoline Leavitt said in a statement Friday. “Biden was seen staring off into the distance and wandering around like a brain-dead zombie, and even had to be ushered by Italy’s Prime Minister Giorgia Meloni.

“Our adversaries like China, Russia, and Iran are no doubt watching Biden’s obvious decline and plotting how they can continue to take advantage of our weak and incompetent Commander-in-Chief,” Leavitt added. “America cannot afford another four years with Crooked Joe at the helm. We need a tough leader with a bold vision to demand peace through strength, and that leader is President Donald J. Trump.”