One of the lobbyists was retained at the direction of the corporation's Republican chairman, Kenneth Y. Tomlinson, they said, and the other at the suggestion of his Republican predecessor, who remains on the board.

The investigators, in the corporation's inspector general's office, are also examining $14,170 in payments made under contracts - which Mr. Tomlinson took the unusual step of signing personally, also without the knowledge of board members - with a man in Indiana who provided him with reports about the political leanings of guests on the "Now" program when its host was Bill Moyers.

While the amounts of the contracts are relatively small, the issues they pose are part of a broader examination by the inspector general of Mr. Tomlinson's efforts to bring what he says is more political balance to public television and radio and what critics say is political interference in programming.

It comes as Republicans in Congress are threatening to cut support for public broadcasting sharply, and as a number of crucial staff members at the corporation have quit and privately cited concerns on Mr. Tomlinson's leadership.

The people who described the inquiry and the declining morale include officials unhappy with the corporation's course under Mr. Tomlinson. Concerned about retribution, they spoke on condition of anonymity.

Mr. Tomlinson, a former editor of Reader's Digest appointed to the board by President Bill Clinton in 2000, said on Wednesday that he would not comment on details of the investigation but was certain that he had done nothing improper.

"We are confident that the inspector general's report will conclude that all personnel arrangements were and continue to be made in accordance with the statutes and rules governing CPB's use of funds," he said in an e-mail message.

Corporation officials said the two lobbyists did not approach lawmakers but provided strategic advice on handling a bill last year that would have given public radio and television stations more representation on the corporation's board. The measure, which died, was opposed by the White House and Mr. Tomlinson but was supported by stations.

One of the lobbyists, Brian Darling, was paid $10,000 for his insights into Senator Conrad Burns, a Montana Republican who sponsored the provision. This year, he briefly served as a top aide to Senator Mel Martinez, Republican of Florida, but resigned after the disclosure that he had written a memorandum describing how to exploit politically the life-support case of Terri Schiavo.

Mr. Darling did not return a telephone call seeking comment.

The other lobbyist, Mark Buse, a former top aide to Senator John McCain, Republican of Arizona, said he provided advice on the legislative process over a month and did not talk to any lawmakers. Mr. Buse, who was paid $5,000, said he was hired at the suggestion of Katherine M. Anderson, a former chairwoman of the corporation and a current board member.

The corporation is financed entirely by taxpayer dollars and is supposed to be a political buffer between lawmakers and public television and radio. For years, it has told groups representing the stations that federal law prohibits it from retaining lobbyists to approach lawmakers or push for legislation.

Mr. Tomlinson has said in recent interviews that he has no desire to impose a political point of view on programming, and that his efforts are intended to help public broadcasting distinguish itself in a 500-channel universe and gain financial and political support. His critics, who include top officials at the Public Broadcasting Service and at National Public Radio, say his actions pose a threat to editorial independence.

The inspector general is looking at contracts signed by Mr. Tomlinson with a man named Fred Mann to monitor the political leanings of "Now." The inquiry was requested by two Democrats, Representatives John D. Dingell of Michigan and David R. Obey of Wisconsin, after they learned about the monitoring.

Officials said the inspector general was examining whether Mr. Tomlinson, as chairman of the corporation, had the authority to approve the contract or the payments.

Mr. Mann, who was listed in the contracts as living in Indianapolis, could not be located, and officials at the corporation said they knew nothing about him.

The inquiry comes as Mr. Tomlinson finds himself at the center of a political battle that threatens to reduce the corporation's budget significantly, and internal turmoil that has sharply eroded morale and recently prompted significant staff defections. The corporation's general counsel, Donna Gregg, left the corporation this month. Last week, Nancy R. Rohrbach, the senior vice president for corporate and public affairs, submitted her resignation.

Ms. Rohrbach has told friends that Mr. Tomlinson repeatedly ignored her advice. She and other officials were described as being upset last week when Mr. Tomlinson rejected a proposed statement by senior officials at the corporation denouncing a vote by a House appropriations subcommittee that would slash the corporation's budget by 25 percent, or $100 million, to $300 million.

The House Appropriations Committee is expected to approve that measure on Thursday.

Officials said that after the panel's vote last Thursday, staff members confronted Mr. Tomlinson about his refusal to approve a statement condemning the Congressional action.

While public television and radio groups denounced the subcommittee vote and called the corporation to seek a similar statement, late in the day Mr. Tomlinson issued a milder response, saying that the corporation was "concerned" and would "be joining with our colleagues in the public broadcasting community to make the case for a higher level of funding as the appropriations measure makes its way through Congress."

The corporation's Democratic and independent members, meanwhile, are preparing to urge the Republican-controlled board to delay the appointment of a new president of the corporation at its regularly scheduled meeting next week. The former president, Kathleen Cox, left in April after her contract was not renewed.

Mr. Tomlinson has said that his top choice is Patricia Harrison, an assistant secretary of state and a former co-chairwoman of the Republican National Committee.