Mark Halperin

Less than 12 hours after sexual harassment allegations surfaced against Mark Halperin, the veteran political journalist has been put on leave by MSNBC, where he had been serving as a contributor. In a statement released Thursday morning, the news network said it finds the allegations first reported by CNN "very troubling."

"Mark Halperin is leaving his role as a contributor until the questions around his past conduct are fully understood," the network said.