The White House on Wednesday rejected Democratic calls to fire the head of the Corporation for Public Broadcasting, who is accused by critics of trying to politicize public television and radio programming.

Asked about a letter from Democratic senators seeking the ouster of corporation Chairman Kenneth Tomlinson, White House spokesman Scott McClellan said, “We continue to support him.”

The Corporation for Public Broadcasting is a federally funded nonprofit and the largest single source of funding for U.S. public television and radio programming. It is governed by a presidentially appointed board.

The letter said Tomlinson had brought a “political agenda” to his job. It accused him of “actively undermining,” underfunding and trying to undo the mission of public broadcasting.

The letter was dated Tuesday and signed by 16 Democratic senators, led by Sen. Charles Schumer of New York and Sen. Dianne Feinstein of California.

“We are writing to urge you to call for the removal of the chairman of the Corporation for Public Broadcasting, Kenneth Tomlinson,” the letter said.

Tomlinson has faulted the television network PBS, which receives funds from the corporation, for “liberal advocacy journalism,” and has sought to bring what he says is “balance” to federally funded public television and radio.

Tomlinson is under investigation by the corporation’s own inspector general over some of his activities, such as a decision to hire outside researchers to gauge whether some public programs had a bias.

The letter from the Democratic senators also accused him of not fighting hard enough against efforts by U.S. House of Representatives lawmakers to make big cuts in the broadcasting corporation’s budget.