Police are searching for a swimmer who vanished during a race down New York's Hudson River on Friday.

Multiple media sources are naming the missing athlete as Dr Charles Van Der Horst, 67, a prominent AIDS researcher and Democrat Party donor from Chapel Hill, North Carolina.

Van Der Horst was taking part in the 8 Bridges Race, a multi-stage 120-mile swimming event down the Hudson.

Friday’s leg spanned 15.7 miles, starting at the Tappan Zee Bridge in upstate New York, and concluding at George Washington Bridge in Manhattan.

The swimmer was reported missing just after 3 p.m. when it was realized that they had failed to finish the event.

Multiple media sources are naming the missing swimmer as Dr Charles Van Der Horst, 67, of Chapel Hill, North Carolina

The New York City Police Department have launched a large scale search, but they have yet to locate the missing swimmer

The New York City Police Department have launched a large scale search, but they have yet to locate the missing person.

New York Water, the organization running the event, canceled Saturday's seventh and final stage of the race.

In a statement they said safety protocols were in place and police were escorting the swimmers during the race.

However, it appears they are preparing for the worst.

Writing on the New York Water website, they wrote: 'It is with great sadness that we report the loss of a swimmer on Stage 6 of the 8 Bridges Open Water Swim.

'Our thoughts are first and foremost with the swimmer's family.'

While the organization would not confirm the identity of the missing person, media sources are naming the swimmer as Van Der Horst.

The doctor's Facebook account lists him as a 'competitive swimmer' and he has shared multiple pictures that show him competing in aquatic events.

Van Der Horst is an internationally known AIDS researcher who previously worked as a professor at the University of North Carolina, Chapel Hill.

Van Der Horst is a top doctor who is an internationally-known AIDS researcher

Van Der Horst is also an outspoken Democrat who endorsed Barack Obama for President in 2008

Van Der Horst was educated at the elite Phillips Academy prep school in Andover, Massachusetts before completing an undergraduate degree at Duke.

He went on to study at Harvard Medical School, and is listed as a former consultant for UNICEF.

Van Der Horst is also an outspoken Democrat who endorsed Barack Obama for President in 2008.

A picture of the doctor with the former Commander-in-chief is featured on his Facebook profile.

He recently told Facebook friends that he was donating money to a variety of Democrats seeking the 2020 nomination.

According to The News & Observer, Van Der Horst was one of 900 protesters arrested during Moral Monday demonstrations in 2013.

The demonstration was held to protest North Carolina's law prohibiting transgender people from using the public restroom of their choice.