President Barack Obama is to leave the White House later this year, his successor yet to be elected.
Polling and bookies puts Clinton out in front ahead of the election in November, but Trump has already defied greater odds just to get the GOP's nomination.
So, in true Obama fashion, he took to the Democratic National Convention to excite the crowd and endorse his former secretary of state to try and secure the presidency for his party.
Here are his best bits:
Donald is not really a plans guy. He's not really a facts guy either.
He calls himself a business guy, which is true, but I know plenty of businessmen and women who have achieved remarkable success without leaving a trail of lawsuits and unpaid workers and people who feel they've been cheated.
On the future:
After almost two terms as your president, I am more optimistic about the future of America than ever before. The America I know is full of courage and optimism and ingenuity. The America I know is decent and generous.
After a century of trying, we declared that health care in America is not a privilege for a few, it is a right for everybody.
Let me tell you, eight years ago, you may remember Hillary and I were rivals for the Democratic nomination. We battled for a year-and- a-half. Let me tell you, it was tough because Hillary was tough. I was worn out.
On Trump again:
Does anyone really believe that a guy who's spent his 70 years on this Earth showing no regard for working people is suddenly going to be your champion? Your voice? Hey, if so, you should vote for him.