WINSTON-SALEM (AFP) - Michelle Obama, surprise star of the 2016 White House campaign, hit the trail on Thursday with Democrat Hillary Clinton as the former and current first ladies fight to conquer battleground states before Election Day.
Obama has emerged as a compelling force in the hard-fought campaign, delivering powerful arguments against Republican Donald Trump and in support of Clinton's bid to become the first female president in US history.
Michelle and Hillary joined forces on the trail for the first time to headline a rally at Wake Forest University in Winston-Salem, North Carolina - a key swing state where early voting is already under way before the November 8 election.
"It doesn't get any better than being here with our most amazing first lady, Michelle Obama," Clinton said as she introduced a "woman whose voice we need now more than ever". Taking the podium, Obama hailed Clinton "for her leadership, for her courage and for what she is going to do for this country." "I don't know about you but I'm fired up! We're going to make this happen," she said.
The 52-year-old wife of President Barack Obama has energised the Democratic camp with a series of speeches taking Trump to task for his strident rhetoric and for what she brands his "frightening" attitude towards women.
And in the closing two weeks of the unprecedented race, Clinton is capitalising on one of the most popular Democrats in America to help make her case.
Clinton holds the momentum as the clock ticks down to Election Day, the polls crediting her with a compelling lead over Trump, but her Republican rival has pledged to pour millions more of his own dollars into his teetering White House bid.
North Carolina voted for Republican nominee Mitt Romney in 2012, but the southern state has been leaning Democratic in the current White House race.
Clinton is relying on strong turnout from the state's substantial African-American population, and a rally featuring Michelle Obama could inspire them to head to polling stations.
Clinton holds a two-point lead there and the state's Republican leaders worry that Trump's slow collapse will hurt them in congressional races.
The latest rolling poll average compiled by tracker RealClearPolitics showed Clinton with a 5.8 point lead in a national race against Trump and two outsiders - pointing to a likely electoral college victory.
"I feel really good, energised, working hard," the former secretary of state told reporters aboard her plane on Wednesday, her 69th birthday.
Trump's standing has been hit hard, particularly among female voters, since this month's release of a 2005 video in which he boasts that his celebrity allows him to grope women with impunity.
But the 70-year-old Manhattan real estate mogul took heart from a new survey that shows him with a two-point lead in early-voting Florida, a state where presidential races are often won and lost.
A combative Trump promised supporters in Ohio on Thursday: "We are going to win back the White House."
"We don't want to give this away," he said. "We are going to Washington, DC. And we are going to drain the swamp." Pressed a day earlier on whether he'll open his own wallet to match an onslaught of Clinton ads, Trump said he will have spent US$100 million (S$139 million) of his own money by Election Day, a sum which would imply him digging much deeper than he has so far.
A Bloomberg poll out on Wednesday put Trump up 45 to 43 per cent among likely voters in the Sunshine State, where Clinton has been campaigning - a close margin in what is a must-win state for him.
The RealClearPolitics poll average still puts Clinton ahead in Florida by 1.6 percentage points. On Friday, President Obama will campaign for Clinton in the state, which he won, albeit narrowly, in both 2008 and 2012.
But Bloomberg's survey shows Trump doing somewhat better than Clinton with independents, who may hold the key to victory in a state that was famously deadlocked in 2000, when the Supreme Court decided the outcome, giving the win to George W Bush.
Trump also appears to have clawed back ground in Nevada, where a new NBC News/Wall Street Journal poll has the western state in a dead heat.
And the provocative billionaire may have found a useful card to play in the final hand: Obamacare.
Republicans have attacked the outgoing president's signature health care reform since it was passed, but they have found new traction after officials confirmed this week that voters' premiums will jump an average of 25 per cent next year.