It’s never good when a news organization loses its political editor just a year before a presidential election. But in the next two weeks, “The PBS NewsHour” will say goodbye not only to its political editor, David Chalian — he is becoming the Washington bureau chief for Yahoo News — but also its managing editor for digital news, Maureen Hoch, who is headed to the World Bank.

They said separately that they were leaving for new professional challenges. But the departures, announced last week, come on top of other changes at the show’s parent, MacNeil/Lehrer Productions, where in recent months both the president and the head of fund-raising and marketing left for other jobs.

In addition, the show’s main corporate underwriter, Chevron, will bow out at the end of the year, leaving a hole of just over $2 million in the $27 million annual budget. A long-planned effort to raise money from wealthy supporters, which was to start last month, has been delayed until the new president of the production company starts in January.

Even Mr. Lehrer’s continuing role on the air with the show that he and Robert MacNeil began in 1975 has become a question.