Democrat presidential hopeful Michael Bloomberg has said that California is a model for the rest of the US, despite the homelessness crisis in Los Angeles.

'I think that California can serve as a great example for the rest of this country,' Bloomberg told supporters at the opening of his Los Angeles campaign office.

The former New York City mayor cited the state's efforts on climate change, gun control and criminal justice reform, as 'something the rest of the country looks up to.'

President Donald Trump has previously said Gov. Gavin Newsom is doing a 'bad job' in the state where homelessness is at crisis levels in Los Angeles and remains high in San Diego, San Jose and San Francisco.

'I think that California can serve as a great example for the rest of this country,' Bloomberg told supporters at the opening of his Los Angeles campaign office.

People experiencing homelessness camp out on the sidewalk of the Skid Row district of Los Angeles, California, USA, 23 December 2019

Trump called California 'a disgrace' last year shortly after its Democratic-controlled Legislature passed a bill that would have required presidential candidates to release their tax returns to get on the 2020 ballot, a proposal aimed squarely at the president. It was later voided in court.

Bloomberg's visit came as part of a swing through a state that he sees as central to his hopes of winning the White House. After a late entry into the race, Bloomberg is bypassing the first four primary and caucus states and is anchoring his strategy to California and other Super Tuesday states on March 3.

His TV ads have been appearing routinely on television, attempting to connect with voters who might know little or nothing about the billionaire businessman.

With more delegates than any other state, California 'has a lot of power in the nominating process,' Bloomberg noted.

His remarks veered from occasional jokes - he lamented that Los Angeles has two strong basketball teams, the Lakers and the Clippers, while the hapless New York Knicks have struggled for decades - to searing attacks on Trump's leadership style and decision-making.

Police officers are checking the pistols traded in by people during the annual gun buy-back event hosted by United Playaz in San Francisco, California, United States on December 14. Bloomberg praised the Golden State for its efforts on gun control

Democratic presidential candidate Michael Bloomberg greets supporters, staff and media at the opening of his downtown Los Angeles headquarters on Monday

Referring to the recent U.S. airstrike that killed top Iranian general Qassem Soleimani, Bloomberg said, 'This president has a habit of making decisions impulsively ... and recklessly, as we've seen time and time again.'

'During crises like this one, it is critically important to ... deescalate tensions and not escalate tensions, and to not speak irresponsibly and make incendiary and bellicose threats that may provoke attacks and endanger our country,' he said.

The political moderate argued that Trump has divided Americans, while he can unite them, and that as Washington languishes in gridlock, he has a record of accomplishment as mayor.

Among the crowd was Los Angeles investor Mike Connolly, who said he feared the Democratic Party was drifting too far to the political left and was drawn to Bloomberg's fiscally conservative, socially liberal blueprint. And, importantly, he believes Bloomberg can defeat Trump.

'He's got the right policies' for most Americans on critical issues like gun violence and climate change, said Connolly, an independent who voted for Presidents Bill Clinton and Barack Obama.

Democratic presidential candidate Michael Bloomberg, center, joins Los Angeles Mayor Eric Garcetti at Philippe The Original, a historic deli serving up signature French dip sandwiches in downtown Los Angeles on Monday

Campaign offices are typically drab affairs located in old storefronts or shopworn, budget-rate offices. But Bloomberg's virtually unlimited budget was on display - his cavernous office was in trendy downtown, its interior accented with industrial chic decor and lush plantings.

Bloomberg earlier joined Mayor Eric Garcetti, a Democrat who flirted with a presidential run, for an early lunch at a downtown restaurant.

'The mayor is paying for it,' Bloomberg quipped. 'Ït's a good deal.'