Andrew McLean is out at Omnicom’s PHD US, according to sources. The agency will be telling the troops later today and announcing his replacement at that time, per sources.

McLean joined the shop as CEO of the PHD U.S. operation in December 2010. Previously, he had been worldwide chief business development officer at WPP’s media management arm GroupM.

The agency is expected to indicate that McLean is leaving to pursue other interests, although sources said his departure is due to a “clash” of personalities. His management style simply did not fit within the agency’s culture. It is unclear what, if anything, brought matters to a head.

On the business front, the agency did not do badly under McLean’s reign. During his first month on the job, the shop won the $1.4 billion U.S. GlaxoSmithKline account after a review that began well before he arrived at the agency. It also won clothing retailer The Gap that same month, with estimated global spending at the time of $350 million.

More recently, PHD US won smaller accounts, like VMware, but also the global $200 million Sony Ericsson assignment.

McLean had succeeded Scott Hagedorn at the agency. Hagedorn shifted to another Omnicom Media Group unit --  the Annalect Group -- a digital and data analytics agency.