'Do for Hillary what you did for me,' Obama urges Americans

"I ask you to do for Hillary what you did for me," Obama told a rally in Ann Arbor, Michigan -- the first of three he is holding for Clinton on the eve of the vote.

"You have the chance to reject a coarse, divisive, mean-spirited politics that would take us backwards," he said. "The chance to elect our first female president."

Obama and his wife Michelle have been among Clinton's most effective champions, drumming up enthusiasm for the former secretary of state as she battled setbacks in the polls.

Michigan, normally a Democratic stronghold, has emerged as a crucial battleground this year, one that Trump, the Republican nominee, hopes will give him a path to victory.

Obama reminded voters that his administration rescued the state's dominant auto industry from the brink of collapse in 2008.

"All that progress goes down the drain if we don't win tomorrow," he said, adding, "This race will be close here in Michigan, just like it will be in a lot of parts of the country."

"I want you just to focus, because the choice you face when you step into the voting booth, it really cannot be clearer. Donald Trump is temperamentally unfit to be commander in chief," he said.

"The good news is, you don't just have to vote against something. You actually have a candidate who's worthy of your vote. A candidate who is smart. A candidate who is steady. A candidate who's tested. Probably the most qualified person ever to run for this office. The next president of the United States -- Hillary Clinton!"

Obama was to rally voters in Durham, New Hampshire later in the day before joining up with Clinton for a big, star-studded campaign event in Philadelphia.

He admitted to experiencing some nostalgia campaigning for what he said was likely to be the last time in a while.