The State Department's chief of protocol is expected to resign over allegations of discrimination and harassment and has been replaced just days ahead of President Trump Donald John TrumpSteele Dossier sub-source was subject of FBI counterintelligence probe Pelosi slams Trump executive order on pre-existing conditions: It 'isn't worth the paper it's signed on' Trump 'no longer angry' at Romney because of Supreme Court stance MORE's trip to Japan for a summit of Group of 20 (G-20) leaders.

NBC News reported Tuesday that Ambassador Sean Lawler informed colleagues that he would resign following Trump's return from the G-20 summit and has been replaced at his position by Mary-Kate Fisher, assistant chief of protocol, who will attend the Japan trip in his stead.

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The State Department declined to comment to NBC News on Lawler's planned resignation or replacement. Lawler was initially appointed to the position in September 2017 by the president and saw a smooth confirmation through the Senate a month later.

Two U.S. officials told NBC News that Lawler was under investigation for improper behavior at the agency, declining to elaborate on the allegations but telling the news outlet that multiple employees had resigned in protest as a result of his actions.

The chief of protocol is in charge of ensuring diplomatic etiquette is followed during domestic and foreign meetings between U.S. officials and their foreign counterparts. The shift in personnel so close to the G-20 summit, where Trump is expected to meet with Chinese President Xi Jinping and possibly Russian President Vladimir Putin Vladimir Vladimirovich PutinPutin nominated for Nobel Peace Prize Navalny released from hospital after suspected poisoning Ex-Trump national security adviser says US leaders 'making it easy for Putin' to meddle MORE, could complicate those efforts.

Trump tweeted earlier this month that Xi had agreed to an "extended meeting" at the summit, which begins Friday, an important moment for the two leaders as the U.S. and China find themselves embroiled in a restarted trade war.

“Had a very good telephone conversation with President Xi of China. We will be having an extended meeting next week at the G-20 in Japan. Our respective teams will begin talks prior to our meeting,” the president tweeted last Tuesday.