The UCSM, which represents every American city with a population greater than 30,000, endorsed the bid at their 84th Annual Conference of Mayors in Indianapolis.

The support of the organisation was put forward to the Tourism, Arts, Parks, Entertainment and Sports Standing Committee by New Orleans Mayor Mitchell J. Landrieu and was then given supported.

Los Angeles 2024 have hailed what they call a “significant endorsement” and claim it further asserts the nationwide support for the bid.

“I am deeply grateful for this resounding show of support from my fellow mayors from all over the United States," Los Angeles Mayor Eric Garcetti, a keen advocate of the bid, said at the Conference. 

"Los Angeles is truly honoured to be America’s Candidate City for the 2024 Olympic and Paralympic Games, and we are determined to live up to the faith the country has shown.

“The level of support for LA 2024 - from the public and from every level of government - is truly extraordinary.

“It demonstrates the growing sense in America that hosting the world’s most important sports event is a once-in-a-generation opportunity to change our communities and our country for the better.”

The support comes after Muriel Bowser, the Mayor of Washington D.C., caused Los Angeles 2024 some embarrassment at the Association of National Olympic Committees General Assembly in the US capital last year October.

She welcomed delegates, including International Olympic Committee President Thomas Bach, by pitching for her city to stage major events, including the Olympic Games.

Bowser concluded by saying: "See you in 2028". 

Speakers at the USCM included Hillary Clinton, the Democrat nomination to run for US President in November.

If Clinton wins, she is expected to play a leading role in Los Angeles' bid. 

Los Angeles 2024 chairman Casey Wasserman believes the “unprecedented” support from the UCSM will inspire the Bid Committee to “pursue the kind of ambitious goals that can have profound, lasting impacts on communities in Los Angeles, across the United States and beyond”.

“LA 2024 has always made it a priority to harness all popular support in the United States for the Olympic Games - whether from the civic pride from previous Games that still resonates today, powerful social legacies like the LA84 Foundation, or excitement about Team USA travelling to Rio 2016 this summer,” he said.

“The Olympics enjoy widespread support in our country, with nine out of ten people across America backing the Games returning to America and now the US Conference of Mayors representing all major US cities endorsing our bid.”

The announcement comes after former Boston 2024 bid leader Steve Pagliuca has been appointed to the Board of Los Angeles 2024 to advise on "strategic planning and financing".

Los Angeles is bidding against Budapest, Paris and Rome.

A final choice is due to be made by the International Olympic Committee at its Session in Lima in September 2017.