New Jersey Governor Phil Murphy is calling on attendees to a Thursday fundraiser at President Trump's golf course in Bedminster, N.J., to quarantine for 14 days. 

"The process for gathering information for case investigation and contact tracing has begun and as far as we know folks are cooperating and we need them to," Murphy said today. 

The president learned that his senior aide, Hope Hicks, had tested positive before he left for New Jersey, according to his chief of staff, Mark Meadows. It's unclear why the trip was not canceled. 

About 100 people attended the part of the event that was held outdoors. But 19 people who paid top dollar for a sit-down conversation with the president met with him inside the club. 

Listen to host David Furst's conversation with reporters Nancy Solomon and Karen Yi about the president's trip to New Jersey on All Things Considered on WNYC.