No Boston Olympics is backing the left-wing Italian Radicals Political Party, which set-up a website last week accompanied by a dossier entitled "Roma 2024: A very risky bet".

Following the launch of the website, Rome 2024 chairman Luca Cordero di Montezemolo said there is "no need" for a referendum given that the City Council voted 38-6 in favour of backing the bid last year.

But No Boston Olympics co-chairman Chris Dempsey disagrees, saying in a statement distributed by the Italian Radicals that "the citizens of Rome deserve the opportunity to have the same sort of debate."

"A referendum – as suggested by Radicali Italiani – is the best way to ensure that happens," he added.

It is likely that 50,000 certified signatures from citizens will be required for a referendum to be held in Rome, followed by a turn-out of at least 50 per cent of eligible voters for validation.

The Radicals party was formed in 2001 but is a relatively small group as they gained just 0.2 per cent of the vote in the 2013 General Election.

The Rome 2024 Bid Committee believes that their candidacy is sustainable as it proposes using existing venues for 70 per cent of the competition arenas, while they have proposed an Athletes Village that can later be transformed into university housing. 

Di Montezemolo, a high-ranking official in the Organising Committee when Italy hosted the 1990 FIFA World Cup, hopes Rome 2024’s candidacy will give the Italian capital a chance to clean up its act in the wake of the beginning of a major mafia trial.

It comes following accusations that a series of criminals in the city scammed millions of euros from city hall contracts for many years.

The Bid Committee chief also estimated that the cost of Rome bidding for the Olympic and Paralympic Games would be around €24.9 million (£19 million/$27.3 million).

This represents a doubling of the original estimate of €10 million (£7.6 million/$10.9 million).

Boston's bid to host the 2024 Games officially came to an end in July after the United States Olympic Committee (USOC) decided that it could no longer continue supporting it.

It followed the announcement of the city's Mayor Marty Walsh that he could not support the bid if that meant signing a host city contract at the time, which the USOC had asked him to do.

No Boston Olympics' objections played a key role, with the group regularly citing economic concerns that come with hosting.

On Sunday (January 10), the first anniversary of the USOC’s decision to select Boston as their contender for the 2024 Games, Walsh claimed the sports world needed to reassess the way in which bids for the Olympics are sold.

He still insisted the bid was an "incredible opportunity" and that they would have done an "incredible job" if they had been selected as the host city by the International Olympic Committee (IOC).

Los Angeles has since been chosen as the replacement American bid, with the USOC admitting they made a "bad call" with their original choice.

"No Boston Olympics welcomes the opportunity to share some of the lessons learned from Boston," Dempsey said in an email sent to the Associated Press.

"It is not for us to tell citizens of Rome what they should do.

"But we do think the IOC offers a fundamentally poor deal to the citizens of host cities.

"The healthy debate that would be spurred by a referendum would bring forward some of those costs and misaligned incentives that might not be apparent at first."

Dempsey also worked with opposition groups in Hamburg, whose residents voted down the city’s potential bid to stage the 2024 Games during a referendum in November.

A referendum could also be held in Budapest with calls gathering pace in Hungary following reports suggesting that a public vote will be held if an opposition initiative attracts 140,000 signatures.

Paris is also in the 2024 bidding race, the winner of which will be decided by the IOC at its Session in Lima in September 2017.