Barack Obama will highlight Hillary Clinton's judgment and toughness on Wednesday as he seeks to boost her campaign to be the first woman U.S. president, hoping to hand off the White House to a trusted fellow Democrat and stop Republican Donald Trump.
On a day when Democrats meeting in Philadelphia planned to tout their candidate as far better suited than Trump to keep the country safe, the Republican gave his critics fresh fodder for attack, with remarks that the Clinton campaign said posed a possible national security threat.
Grabbing the spotlight at a news conference in Miami, Trump urged Russia to find and release tens of thousands of emails that Clinton did not hand over to U.S. officials as part of a probe into her use of a private email system while she was secretary of state. Clinton has said the emails she did not hand over were private.
Wednesday's events at the party's national convention were aimed at contrasting the 68-year-old Clinton's foreign policy skills with Trump's "unsteady, unfit and dangerous approach," Clinton campaign chair John Podesta said earlier.
Clinton secured the party's nomination on Tuesday. When she formally accepts it on Thursday, she will become the Democratic standard-bearer against Trump in the Nov. 8 election.
Trump, a 70-year-old New York businessman with no experience in political office, has hammered Clinton as untrustworthy and cast America as a place where security threats abound and law and order are breaking down. He has proposed deeply controversial measures such as temporarily banning Muslims from entering the country and building a wall on the border with Mexico border to stop illegal immigrants.
The Clinton campaign portrays Trump, a former reality TV star, as temperamentally unfit for the White House.
Obama offered a preview of his evening speech in an interview with NBC News broadcast on Wednesday.
"I hope my headline (from the speech) is that the president of the United States is profoundly optimistic about America's future and is 100 percent convinced that Hillary Clinton can be a great president," the president said.