The US Democratic presidential candidate is boosted by endorsements from his former rivals.
By Mike Hills
His campaign lost momentum despite a successful start
The 38-year-old dropped out ahead of Super Tuesday votes in 14 US states.
The way Democrats pick a nominee takes months, costs a fortune and doesn't even lead to high turnout.
Former Mayor Pete Buttigieg addressed Senator Amy Klobuchar's stumble over Mexico president's name.
By Anthony Zurcher
North America reporter
New entrant Michael Bloomberg comes under fire in the race for the Democratic presidential nomination.
The billionaire, former New York mayor faced his rivals for the first time