A bond insurer threw a wrench in the works during Detroit's bankruptcy proceedings on Wednesday by presenting four possible bids for the city's art.

The city has been working on a "Grand Bargain," outlined by a bankruptcy judge, to transfer city-owned artwork to a nonprofit owner, settling some debt and safeguarding the art with about $816 million in funds from philanathropic groups, the state of Michigan and other supporters.

Now, four "expressions of interest" over works in the Detroit Institute of Arts collection have been aired in court and are said to represent more money for the city's creditors.

Detroit hammered out a settlement on Wednesday to pay retirees 74% of their owed pensions, with 26% going to a fund for the most vulnerable retirees. Detroit's retirees are facing a pension fund that is short by $3.5 billion and there is no funding in their health plan.

Finanical Guaranty, backed by other of the city's creditors, wants to get the maximum amount on pay claims and presented Detroit's bankruptcy judge, Steven Rhodes, with the potential bids.

Among the possible offers is a 20-year, $2 billion loan to Detroit from Art Capital Group, the firm that held the photographs of Annie Leibovitz as collateral for a loan. She had to sell her Greenwich Village home to pay back the loan.

An offer of $1.75 billion for the museum's collection came from Catalyst Acquisitions and Marc Bell Captial Partners. A client of Beijing Poly International Auction House is said to have offered "up to $1-billion" for all the Chinese art in the collection. Sheng Yuan Management Hong Kong Limited had a bid from clients of up to $1.473 for 116 Chinese works.

Mediators are currently working with Detroit's creditors. Whether Judge Rhodes has the authority to carry out the "Grand Bargain" and if the city's art is safe from sales under Chapter 9 protection is still on the line.