White House Chief of Staff John Kelly watches as President Donald Trump speaks during a meeting with North Korean defectors in the Oval Office at the White House in Washington, DC on Friday, Feb. 02, 2018.

White House chief of staff John Kelly said that President Donald Trump is "embarrassed" by special counsel Robert Mueller's probe into potential collusion between Trump's 2016 campaign and the Kremlin.

In an NPR interview that aired Friday, Kelly suggested that the investigation is the elephant in the room when foreign leaders visit the president.

"When world leaders come in, it's kind of like, you know, Bibi Netanyahu is here and he, who's under investigation himself, and it's like, you know, you walk in and, you know, the first couple of minutes of every conversation might revolve around that kind of thing," Kelly said. Israeli Prime Minister Netanyahu, who met with Trump at the White House in March, faces a corruption investigation in Israel.

"It may not be a cloud but certainly the president is, you know, somewhat embarrassed, frankly," added Kelly, a retired four-star Marine general.

Trump has referred to the investigation as a cloud over his presidency, according to accounts from former FBI Director James Comey, whom Trump fired May 9, 2017. Trump later told NBC News' Lester Holt that he was thinking about the Russia investigation when he decided to fire Comey. The FBI chief's termination eventually led to the appointment of Mueller to take over the probe.

The president often describes the investigation as a "witch hunt" and has repeatedly denied claims of collusion and obstruction of justice, which is another area Mueller's team is reportedly investigating.

Kelly's comments to NPR came after Vice President Mike Pence said that the special counsel's investigation should come to an end. "In the interests of the country, I think it's time to wrap it up," Pence told NBC's "Today Show" on Thursday.

Kelly also suggested that the probe had gone on too long.

"Something that has gone on this long without any real meat on the bone, it suggests to me that there is nothing there, relative to our president," Kelly told NPR.

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