At her last Television Critics Association press tour as president and CEO of PBS, Pat Mitchell said it’s getting more difficult to secure financial resources to provide the kind of programming the public service’s mandate requires.

“It’s getting harder and harder, year after year, to bring the programs we want to bring to public television,” Ms. Mitchell said during PBS’s executive session Saturday at the TCA Winter Press Tour in Pasadena, Calif.

Asked by a reporter what she wishes she had fixed in her six years of running PBS, Ms. Mitchell said she was proud of the establishment of the PBS Foundation but had hoped to supply it with more than the $13 million currently set aside for long-term programming needs.

Getting beyond pledge drives to raise funds is also an ongoing challenge, she said.

“The dependence on pledging and membership drives is something all of us know we have to look at and transition to other forms of fund-raising,” she said. “It is still the largest source of revenue. Clearly we couldn’t take it and pull it out. We didn’t find a solution, and that’s probably because there isn’t an easy thing you can slot in, in terms of return and relationships with the community.”

PBS continues to look for an underwriter for “Masterpiece Theatre,” which is still hamstrung by the loss of ExxonMobil as a major sponsor more than two years ago. Part of the problem is changes in the way major companies look at sponsorships, she said.

“They are making different kinds of measurements,” she said of potential underwriters. “The whole sponsorship model is just being turned on its head. Ad agencies are trying to figure out where to move their money, on television or online. We are caught up in this incredible time of change.”

Several reporters threw out suggested partners for PBS on “Masterpiece,” including talk show host and producer Oprah Winfrey. Ms. Mitchell said PBS had approached Ms. Winfrey about a partnership, then asked Rebecca Eaton, executive producer of “Masterpiece,” to elaborate.

“We did contact Harpo Productions about the possibility of doing miniseries of Oprah book club books,” Ms. Eaton said. “We thought it was a no-brainer. That was about two years ago and they said their plate was full. Then ExxonMobil left. Now the time might be right to go back.”

Reporters gave Ms. Mitchell more than a few chances to take some parting shots at her critics and challengers, but for the most part she declined, except to say former Corporation for Public Broadcasting Chairman Kenneth Tomlinson, who left his job last year amid allegations that he had politicized his position, had “misinterpreted his responsibilities.”

“His responsibility was to protect PBS from being a political minefield,” she said. “He didn’t do that. He went public with his criticism, and that’s regrettable.”

PBS also made a number of programming announcements at the session: