'I believe in Hillary Clinton,' Obama tells voters

PIC: US President Barack Obama and Democratic presidential candidate Hillary Clinton leave the campaign event in Charlotte, North Carolina, on Tuesday. (AFP)

President Barack Obama made a dramatic return to the campaign trail at Hillary Clinton's side Tuesday, throwing his full weight -- and compelling oratory -- behind her bid to succeed him in the White House.

Obama has been off the campaign trail for years, but the president made a passionate case for Clinton in their first joint appearance of the 2016 race, as he celebrated her character and castigated her Republican rival Donald Trump.

"I'm here today because I believe in Hillary Clinton," Obama told the rally in Charlotte, North Carolina taking place just hours after the FBI's bombshell announcement that it will not recommend charges over Clinton's email practices while she was Obama's secretary of state.

The two took the stage to ecstatic cheers from supporters, with Obama leading the crowd in chants of "Hillary! Hillary!" and the Democratic duo locking hands and raising them in a victory wave.

Clinton was decked out in a bright fuchsia-colored suit, while Obama was in prime campaign trail outfit: white dress shirt with his sleeves rolled up.

The pair traveled together on Air Force One for the first in a series of high-profile events intended to give the presumptive Democratic nominee a boost in her November showdown with Trump.

"There has never been any man or woman more qualified for this office. Ever!" Obama told the crowd.

"Let me tell you, North Carolina, my faith in Hillary Clinton has always been rewarded," the president said in a vibrant speech in support of the former senator and first lady.

"I have had a front-row seat to her judgment and her toughness and her commitment to diplomacy."

"She is and will be a stateswoman who makes us proud around the world," Obama said. "I am ready to pass the baton. And I know that she is going to take it."

Appealing to working American families, the president assailed the presumptive Republican nominee Trump for his "phony bluster" and warned, repeatedly: "The other side's got nothing to offer you."

'Shoulder to shoulder'

Neither Clinton nor Obama made any mention of the FBI's recommendation to the Justice Department.

The announcement takes a weight off Clinton, whose campaign has been dogged by the scandal.

But the FBI's assessment, which found that Clinton was "extremely careless" in sending classified information via her personal email account, is far from the complete exoneration she had hoped for.

Clinton highlighted how she and Obama grew from adversaries to allies, with the unspoken signal that she expects supporters of her primary campaign rival Bernie Sanders to soon get on board her campaign.

"Through it all, as we went from political rivals to partners to friends, my esteem for him just kept growing," Clinton said.

Obama too recalled his bitter primary battle with Clinton and how it morphed into a fonder relationship.

"We may have gone toe to toe, from coast to coast, but we stood shoulder to shoulder for the ideals that we share," Obama said.

Both blasted Trump as temperamentally unfit to be president, and rally attendee Carolyn Chabora, a self-described lifelong Republican, agreed.

Chabora, 71, had backed Republican Jeb Bush, but she winced when asked about why she was at a Clinton rally and not on board with Trump.

"Donald Trump is insolent, he's rude, he's a bully, he's a misogynist, he is disdainful, contemptuous. He has no experience," she told AFP.

"Hillary Clinton is experienced. She's smart," added Chabora, who wore a shirt that read "Republican women for Hillary."

"She will be a wonderful president."

Marketing consultant Kathleen Tunson was thrilled Obama joined Clinton in Charlotte.

"It helps her campaign, shows the solidarity of the Democratic Party," Tunson said. "It's important for him to be here supporting her."