Barack Obama to pitch for Hillary Clinton as having the judgment for the White House

Barack Obama will add an optimistic pitch on Wednesday to the campaign to elect Hillary Clinton as the first woman US president, as he seeks to hand off the White House to a trusted fellow Democrat and stop Republican Donald Trump.

Clinton formally secured the Democratic Party's presidential nomination on Tuesday, coming back from a stinging defeat to Obama in her first White House run in 2008 and surviving a bitter primary fight against Bernie Sanders to become the first woman to head the ticket of a major US party.

The 68-year-old former secretary of state will accept the nomination on the last day of the party's convention in Philadelphia on Thursday, becoming the Democratic standard-bearer against Trump in the Nov. 8 election.

Obama, due to address the meeting on Wednesday evening, has been vocally critical of the Republican candidate, and is likely to contrast his optimistic view of the United States with Trump's darker vision, on a day when the convention will focus on national security.

The New York businessman has cast America as a place in need of a strong leader, where security threats abound and law and order are breaking down. Trump, 70, has proposed deeply controversial measures such as temporarily banning Muslims from entering the country and building a wall on the Mexico border to stop illegal immigrants.

"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," Obama said in an interview with NBC News that aired on Wednesday.

His remarks will follow his wife Michelle Obama's opening night speech to the gathering on Monday, which was a rousing success with delegates. "I'm not going to hit that bar, so let me concede top speech-making already to my wife, but I couldn't have been prouder of her," Obama said.

Obama "has been candid about why he thinks electing the Republican nominee is a risky path for the United States," White House spokesman Eric Schultz said on Tuesday. But Obama's speech will focus more "on how Secretary Clinton has the judgment, the toughness and the intellect to succeed him in the Oval Office," Schultz said.

The Clinton campaign portrays Trump, a former reality TV star whose campaign style has been freewheeling and whose remarks have been peppered with insults, as temperamentally unfit for the White House.

The convention aimed to reinforce this message on Wednesday. Events would seek to contrast Clinton's approach to national security with Trump's "unsteady, unfit and dangerous approach," said Clinton campaign chair John Podesta.

Trump has accused Obama and Clinton of being far too weak on the threat posed by Islamist militants such as Islamic State. "There is no more urgent priority to (Clinton) than making sure that the threat of radical jihadist terrorism (...) is stopped," Clinton foreign policy adviser Jake Sullivan told reporters, adding that speakers would seek to highlight Clinton's foreign policy experience.

"Donald Trump has disrespected our military, and I think that will shine through tonight," Sullivan said. Obama, who beat Clinton in the 2008 campaign for the Democratic nomination, will be speaking 12 years to the day since he gave a keynote address as a US senator to the Democratic convention in 2004, which effectively launched him on the national stage. Clinton waged another hard-fought primary battle this year, beating off an unexpectedly strong challenge from the left by Sanders, a US senator from Vermont.

STAR LINE-UP

The Democrats have sought to buttress Clinton with a star gathering of current and past party notables in Philadelphia. As well as Obama, speakers on Wednesday will include Clinton's vice presidential running mate, Tim Kaine, Vice President Joe Biden, former New York Mayor Michael Bloomberg and Leon Panetta, a former defense secretary and former head of the CIA.

Bloomberg, founder of the Bloomberg news and data service, was previously elected as a Republican and later became an independent. Bloomberg would take on Trump in the area where the New York real estate developer seeks to appeal to voters: his business acumen, said campaign chair Podesta.

"He (Bloomberg) will talk about the reason he has come to the conclusion that Hillary Clinton is the right choice to be a stable leader on economic matters, and why Donald Trump through his life in business is incapable of managing the economy let alone his own affairs," Podesta said.

Bloomberg, one of the founders of a mayors' initiative against illegal guns, is also a strong ally to Clinton in her efforts to reduce gun violence. Kaine will also get a chance to present himself to the party. Announcing her choice of running mate last week, Clinton cast the US senator from Virginia as a seasoned and steady leader and a contrast with Trump's volatile campaign. But the pick disappointed some supporters of Sanders who were upset over Kaine's past support for the Trans-Pacific Partnership trade agreement.

HISTORY IS MADE

On Tuesday night, Democrats reveled in history being made.

Addressing the gathering, former President Bill Clinton called his wife, who has also been a US senator, a dynamic force for change. Bill Clinton also sought to paint his wife in a warm, personal light, countering the Republican portrayal of her as a power-hungry politician who bends the rules and lacks transparency in her political dealings.

Controversy over her use of a private email server for official business while she was secretary of state from 2009-2013 dogged her during the campaign, and more than half of American voters view her unfavorably, according to Reuters/Ipsos polling.

Trump, who has never held elective office, is even less popular, with 61 percent holding an unfavorable view, the polling showed. Trump got a boost in opinion polls from his nomination at the Republican convention in Cleveland last week. He had a 2-percentage-point lead over Clinton in a Reuters/Ipsos poll released on Tuesday, the first time he has been ahead in this survey since early May.