Barack Obama backs Hillary Clinton to guard his legacy

His own legacy on the line, US president Barack Obama implored Americans to elect Hillary Clinton to the White House, casting her as a candidate who believes in the optimism that drives the nation’s democracy and warning against the “deeply pessimistic vision” of Republican Donald Trump.

“America is already great. America is already strong,” he told cheering delegates at the Democratic convention on Wednesday night.

“And I promise you, our strength, our greatness, does not depend on Donald Trump.”

For Democrats, the night was steeped in symbolism, the passing of the baton from a barrier-breaking president to a candidate trying to make history herself.

It culminated with Ms Clinton making a surprise appearance on stage to embrace Mr Obama, an image almost unimaginable eight years ago when they battled for the Democratic nomination.

Mr Obama urged Americans to summon the hopefulness of that White House campaign, before recession deepened and new terror threats shook voters’ sense of security.

He robustly vouched for Ms Clinton’s readiness to finish the job he started, saying “no matter how daunting the odds, no matter how much people try to knock her down, she never, ever quits”.

Earlier Wednesday, Ms Clinton’s running mate, Virginia senator Tim Kaine, introduced himself to the nation as a formidable foil to Mr Trump in his own right. With folksy charm, he ridiculed Mr Trump’s list of promises and one of the GOP candidate’s favorite phrases.

“Believe me!” he said mockingly, as the audience boomed back, “No!”

Liberals, particularly those who supported Vermont senator Bernie Sanders, have grumbled about Mr Kaine being on the ticket, particularly because of his support for fast-track approval of the Trans-Pacific Partnership trade pact. Several delegates held up anti-TPP signs as he spoke.

Mr Obama’s support for Ms Clinton is driven in part by concern that Mr Trump might win in November and unravel his two terms in office. He warned repeatedly that the billionaire businessman is unprepared for the challenges of the Oval Office.

Wednesday night’s Democratic lineup was aimed at emphasising Ms Clinton’s national security credentials.

It was a significant shift in tone after two nights spent reintroducing Ms Clinton to voters as a champion for children and families, and relishing in her historic nomination as the first woman to lead a major political party into the general election.

The core of Ms Clinton’s strategy is putting back together Mr Obama’s winning White House coalition. In both his campaigns, Obama carried more than 90% of black voters, the overwhelming majority of Hispanics, and more than half of young people and women.