In the latest attempt to crack down on potentially embarrassing digital leaks from presidential fundraisers, President Barack Obama’s campaign has begun asking donors attending small fundraisers with the president to turn over their cell phones before entering.

Pool reporter David Nakamura of the Washington Post reported that at a $35,800 a head fundraiser at the home of Blackstone COO Hamilton “Tony” James in New York City Monday night, the 60 attendees were asked to place their phones in plastic bags by the door.

An Obama aide called the move it “standard operating procedure,” but veterans of a range of other campaigns said they’d never heard of the practice, which is common in secure White House spaces where there are concerns of espionage, but unknown in contexts in which only political secrets are discussed. The new prevalence of sophisticated audio and recording capacities in mobile devices owned by virtually anyone wealthy enough to write a check to a political campaign, however, has put a new pressure on campaigns concerned with staying on a public message.