White House chief of staff denies reports he called Trump an 'idiot'

White House Chief of Staff John Kelly took the rare step of issuing a swift, public denial to a new report that alleges he called President Donald Trump an "idiot" in recent months amid an allegedly increasingly acrimonious relationship with his boss.

"I spend more time with the president than anyone else and we have an incredibly candid and strong relationship," Kelly said in a statement. "He always knows where I stand and he and I both know this story is total BS."

"I am committed to the president, his agenda, and our country," Kelly added. "This is another pathetic attempt to smear people close to President Trump and distract from the administration's many successes."

Zach Fuentes, assistant to the chief of staff and special assistant to the president, reaffirmed Kelly's statement, telling ABC News the story is "complete BS."

"He never said that," Fuentes said. "I was in the meeting."

The original blistering report from NBC News details repeated instances in which Kelly insulted the president.

In one meeting, Kelly reportedly said, "He doesn't even understand what DACA is. He's an idiot," and allegedly added, "We've got to save him from himself."

The NBC News story, which cites four anonymous sources, also claims Kelly boasted, "I'm the one saving the country" on several occasions, and damaged morale in the West Wing with disparaging comments about women being "more emotional than men."

CNN also reported Monday that in what "appeared to be a moment of frustration," Kelly said he believed the president "was becoming unhinged."

This comment came during a meeting with Secretary of Defense James Mattis, Chairman of the Joint Chiefs of Staff Joseph Dunford and senior National Security Council officials, according to CNN.

Trump ardently rebuked the reports via Twitter Monday evening, calling them "false stories" that used "only unnamed sources."

The president also insisted that the White House "is running very smoothly."

This is not the first time during Kelly's nine-month tenure as chief of staff that the four-star Marine Corps general has been the subject of controversy or linked to chaos inside the White House.

In February, Kelly came under fire for his role in the ousting of former White House staff secretary Rob Porter. The chief of staff defended Porter amid allegations of domestic abuse, calling him "a man of true integrity and honor."

Kelly was criticized for his handling of the scandal, including by the president. Two days after Porter resigned, ABC News reported that Trump was so furious over Kelly's handling of the situation that he spoke with confidants about possibly replacing Kelly.

In January, Kelly told Fox News in an interview that his boss "has evolved" since becoming president, appearing to embarrass Trump.

"He has evolved in the way he's looked at things," Kelly said. "Campaigns and governing are two different things."

Trump contradicted Kelly's statement shortly after, writing on Twitter, "The Wall is the Wall, it has never changed or evolved from the first day I conceived it."

Last month, however, Trump struck a more adulatory tone with Kelly during a visit to the Marine Corps Air Station Miramar, praising the general on his job performance.

"He's doing a great job in Washington," Trump said of Kelly during his remarks.

Despite Monday's reports of a divide between Trump and his chief of staff, sources told ABC News that the two currently stand on solid ground.

ABC News' Meridith McGraw contributed to this report.