Political journalist Mark Halperin built an industry on tracking the fortunes of the flawed characters he followed through campaign seasons. He gleefully chronicled who was up and who was down in his best-selling books and television coverage, and made himself into one of the most prominent and most highly remunerated journalists in the country.

The drama and intrigue came to him Wednesday night, when CNN posted a detailed report that he had sexually harassed women years ago, when he worked as director of political coverage at ABC News. The CNN report included interviews with five women it did not identify who said Halperin had made unwanted sexual advances against them.

On Thursday morning, MSNBC, the cable network where he is a political analyst and appears frequently on the influential show “Morning Joe,’’ announced that he would no longer be a contributor.

In a statement, an MSNBC spokesman said, “We find the story and the allegations very troubling. Mark Halperin is leaving his role as a contributor until the questions around his past conduct are fully understood.’’

Later, HBO said it had dropped plans to produce a film based on an upcoming book by Halperin and John Heilemann about the 2016 election.

The movie would have been a sequel of sorts to “Game Change,’’ the Emmy Award-winning HBO film adapted from their book about the presidential race in 2008.

“HBO has no tolerance for sexual harassment within the company or its productions,’’ the network said in a statement.

Through a spokesman, Halperin, issued the following statement: “During this period, I did pursue relationships with women that I worked with, including some junior to me. I now understand from these accounts that my behavior was inappropriate and caused others pain. For that, I am deeply sorry and I apologize. Under the circumstances, I’m going to take a step back from my day-to-day work while I properly deal with this situation.’’

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