The president of the National Association of Realtors resigned Monday after allegedly receiving a blackmail threat, the latest in a series of blows to the giant U.S. trade organization that represents more than 1.5 million real-estate agents. 

Tracy Kasper received a recent threat to disclose a past personal matter unless she “compromised her position at NAR,” according to an NAR statement. She refused and reported the threat to law enforcement, then decided to step down, the statement said.