The chairman of the agency that oversees Voice of America and other government broadcasts to foreign countries said yesterday he would not seek renomination, likely ending a series of ethical controversies that have clouded his tenure.

Kenneth Y. Tomlinson asked President Bush not to submit his name for reconfirmation as chairman of the Broadcasting Board of Governors, which runs VOA, Radio Free Europe and Alhurra, the pan-Arabic satellite TV channel funded by the United States.

"I have concluded that it would be far more constructive to write a book on my experiences rather than to seek to continue government service," Tomlinson wrote. "Accordingly, I ask that you nominate another person to serve as chairman of this board."

The letter was something of a formality. With the Democrats controlling the Senate, Tomlinson -- a longtime Republican colleague of White House adviser Karl Rove -- would have faced long odds of confirmation. He has been under fire at least twice in the past 18 months for his performance in two appointed jobs.

According to a report last summer by the State Department's inspector general, Tomlinson violated federal rules by running his private horse breeding and racing operations out of his government office and improperly put a friend on the broadcasting board's payroll.

In late 2005, Tomlinson essentially was ousted from the board of the Corporation for Public Broadcasting, which distributes federal funds to public broadcasters such as PBS and National Public Radio. The corporation's inspector general found that he had violated agency rules by exerting political influence over public television and radio. In an effort to introduce conservative-oriented programming on NPR and PBS, Tomlinson secretly commissioned content studies and helped steer federal production funds to favored producers, according to the inspector general.

In an interview yesterday, Tomlinson said that he did nothing wrong in both cases and that his critics were attempting to "criminalize political differences."

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