By Steve Holland

WASHINGTON (Reuters) - Jordan Karem, one of President Donald Trump's longest serving aides, plans to leave the White House by the end of the year to return to the private sector, White House officials said on Monday.

Karem, 37, told Trump on Monday morning of his plans to depart, the officials said.

Since March, Karem has been deputy assistant to the president and director of Oval Office operations. He is known as the president's "body guy," a personal aide who is the first White House official to see Trump in the morning and last to see him at night, tasked with keeping him on schedule and briefing him on upcoming meetings and events.

Nicholas Luna, the White House trip director, is the likely successor to Karem, the White House officials said.

“Jordan Karem is great guy who I have gotten to know well over the last several years," Trump said in a statement in response to queries about Karem. "He was with me from the beginning and I appreciate his loyalty and his commitment to my administration. He did an excellent job working with me and my team."

The period after midterm congressional elections is a typical time for White House turnover. Karem has told colleagues he wants to return to the energy sector, where he worked prior to service for the president, and start a family with his wife, who he married early this year.

Karem, a veteran of Republican Party politics, began working for Trump as a campaign aide in July 2015 shortly after the New York real estate developer began his bid for the Republican presidential nomination.

He ended up the campaign as press director for Trump's vice presidential running mate, Mike Pence, and began his tenure at the Trump White House as the overall director of presidential advance.

(Reporting By Steve Holland; Editing by Bill Trott)