Barack Obama blasted Donald Trump as being unqualified to be president as he addressed a fundraising event for Hillary Clinton.
He praised the Democratic Party presidential nominee as someone who cares deeply about making sure that the United States works for everybody and not just a few.
On the New York home turf of Mr Trump, her Republican Party rival, Mr Obama dismissed the tycoon as "the other guy" and said he is not qualified to be president.
The president was talking to about 65 people at the event at the home of restaurateur Danny Meyer.
Attendees contributed $25,000 while others paid up to $250,000.
Mr Obama said Mrs Clinton's judgement has been "unerring".
He also said she has been disciplined and "extraordinarily effective" in every job she has ever had.