The WPP-owned public relations firm Burson-Marsteller today named Donald Baer, a former White House communications director under President Bill Clinton, as its worldwide CEO. He succeeds Mark Penn, who is heading in-house with longtime client Microsoft as corporate vice president for strategic and special projects, according to a statement today from Burson-Marsteller.

Baer joined the company four years ago and has also served as chairman of Burson-Marsteller’s sister research firm, Penn Schoen Berland. He will continue in that role.

“Burson-Marsteller continues to be an industry leader with strategic public relations capabilities and a global footprint that few firms can match,” said WPP CEO Martin Sorrell in the company’s press release. “I am confident the firm’s track record of success and its reputation for delivering results for its clients will continue under Don Baer’s leadership.”

The move comes at a time when some of WPP’s Washington, D.C., properties — which include communications and lobbying shops such as QGA Public Affairs and Ogilvy Government Relations — have experienced staff departures.

Baer has a long resume that includes a stint as a top executive at Discovery Communications and as a journalist for such publications as U.S. News & World Report.