The city of Boston has pulled out its bid to host the 2024 Olympics. This was announced by Boston Mayor Marty Walsh at a press conference Monday.

"If committing to sign a guarantee today is what's required to move forward, then Boston is no longer pursuing the 2024 Olympic and Paralympic Games," Walsh said.

As noted by Boston.com, Walsh has supported the city's Olympic aspirations since last fall despite significant public pushback. The report points out that the host city contract includes the requirement that the city agree to cover any financial shortfalls of the Olympics"”an issue that has become the most contentious surrounding the bids.

I cannot commit to putting tax payers at risk," the mayor said, while also indicating that he has been pressured by the United States Olympic Committee to say he would agree to sign the host city contract should Boston win the right to host the 2024 Summer Games.

Previously, Olympic organizing group Boston 2024 said it would put in a multi-faceted insurance policy in place, which would protect the city from the threat of cost overruns, as pointed out by the Boston.com report. And while the group has published some details of the plan last week, Walsh said they have been unable to conclude its analysis of the bid's risk.

Jay Busbee of Fourth Place Medal notes that the costs for the Olympic Games have spiraled in recent years, with both Beijing ($43 billion in 2008) and Sochi ($51 billion in 2014) compiling "astronomical preparatory costs." The report also notes that while Boston would most likely not incur significant costs due to existing facilities, the International Olympic Committee's expectation that a host city should shoulder all the costs is not an acceptable proposition for most 21st century cities.

Busbee also notes that of the six cities bidding for the 2022 Winter Games, only China and Kazakhstan are left making bids.