Washington(CNN) President Donald Trump's longtime aide and current director of Oval Office operations Keith Schiller has told people he intends to leave the White House, three sources familiar with the decision told CNN.

Schiller has told associates within the last two weeks that he plans to leave the White House at the end of September or in early October, the sources said. Schiller has told people his primary reason for leaving was financial, the sources said. Schiller earns a $165,000 annual salary at the White House -- a downgrade from his annual earnings before he followed Trump to the White House.

Schiller's planned departure comes just over a month after Kelly became chief of staff with the mission of instilling new order inside Trump's often chaotic White House. But Trump has chafed at some of Kelly's attempts to restrict access to the President.

Now, Schiller's potential departure will leave Trump without one of his most loyal and trusted aides at his side at a time of tumultuous change at the White House. Schiller has been a constant presence at Trump's side for nearly two decades and was among a handful of aides from Trump's previous life as a businessman to follow Trump onto the campaign trail and into the White House.

White House press secretary Sarah Huckabee Sanders said the story was "not true" and declined to comment further. Schiller declined to comment.

It is unclear whether Schiller will be convinced to stay longer in his position.

Schiller's White House salary was a decrease in income from his pre-White House time at Trump's side, when he earned $294,000 from his employment at the Trump Organization, Trump campaign and his private security firm, KS Global Group last year, according to a financial disclosure released by the White House earlier this year.

The sources stressed that Schiller's reasoning was primarily financial, but one source said Schiller has also grown frustrated with the new system installed by White House chief of staff John Kelly aimed at restricting access to the President. Schiller has complained that he must call into the White House switchboard to reach Trump over the phone, one source said.

The former New York Police Department detective was entrusted with one of the most sensitive and controversial decisions of Trump's presidency, delivering a letter to FBI headquarters notifying then-FBI Director James Comey that Trump had decided to fire him.

As Trump continues to grapple with Kelly's more isolating measures, just two close aides who worked for Trump at the Trump Organization will remain at Trump's side: Hope Hicks, the White House communications director, and Dan Scavino, the social media director.

While Trump's other personal bodyguards left when the Secret Service took over as Trump's protective detail, Schiller remained at Trump's side, serving as a body man and personal aide who often had the best sense of Trump's mood and needs during the campaign.

The 6'4'' longtime aide also took on the task of removing the protesters who frequently disrupted Trump's rallies during the campaign.

Schiller first entered Trump's orbit while he was still an NYPD detective in 1999, snagging a part-time gig doing bodyguard work for Trump. Eventually, Schiller left the NYPD and became Trump's full-time bodyguard and later his head of security in 2005.