The Santa Rosa City Council this week granted a fourth contract extension to a developer hoping to construct a 10-story mixed-use tower downtown.

Hugh Futrell and partners will now have until the end of 2013 to close escrow on the city-owned former AT&T building.

The demise of the city's redevelopment agency has created uncertainty for lenders, investors and title companies, contributing to the project's inability to obtain tax-credit financing this year, city officials said. Futrell hopes to secure that financing in early 2013.

The Museum on the Square is the city's most anticipated downtown development project. It would transform an empty concrete eyesore into a glass-clad tower with space on the first floor for the Sonoma County Museum and a restaurant, four stories of offices, and five new stories for apartments.

The city's redevelopment agency purchased the building in 2007 for $3 million in the hopes of spurring development on the site.