Sony Entertainment CEO Michael Lynton informed President Obama on Thursday that he was stepping down from his seat on the Broadcasting Board of Governors, apparently over time commitments.

In a letter to Obama, Lynton said that “circumstances kept me from taking part” in recent formal meetings of the board. He has served since July 2, 2010, with a term that runs through August. But by law, any member can serve on the board until a successor is appointed. Lynton was appointed interim presiding governor in February, 2012 after Walter Isaacson stepped down from his post as chairman.

The board overseas the U.S. government’s international broadcasting efforts, including Voice of America.

Lynton said in his letter that he was “was proud to work with fellow board members on promoting long-needed reforms of the agency’s structure and governance– among them, enhancing collaboration between the broadcasters and establishing the position of a Chief Executive Officer with day-to-day operational responsibilities.”

“It has been an honor to serve our country by taking part in the work of this board, which was established to oversee an agency with a complex and vital calling,” Lynton wrote to  Obama. “Time and time again, we have seen that the journalists and other staff of the BBG are dedicated to the agency’s mission: to inform, engage and connect people around the world in support of freedom and democracy. They prove it around the clock and against steep odds, in many cases amid some of the most difficult circumstances imaginable.”

Chicago Sun-Times’ White House correspondent Lynn Sweet wrote that she recently raised questions about Lynton’s attendance record at board meetings.

A State Department Inspector General’s report, released in January, included substantial criticisms of the agency, including that “chronic vacancies and absences of Board members threaten the quorum required for the Board to act, limit the diversity of perspectives brought to discussion, and put at risk the bipartisan nature of the Board.”

The report also recommended a CEO position, and the BBG has been outlining such a position in budget requests.

Lynton’s departure leaves the board with four members, including Secretary of State John Kerry, who serves as an ex officio member.