A contentious proposal to demolish an office building on Hamilton Avenue and replace it with a mixed-use development with roughly twice the square footage fizzled Monday night after fierce backlash from the surrounding community.

Without taking any formal votes, the Palo Alto City Council swiftly struck down a project that a developer was considering for 550 Hamilton Ave., currently the site of a three-story office building.

Under the proposal by developer C.M. Capital, that 43,272-square-foot building would be demolished and replaced with a 57,475-square-foot office building. The developer also proposed adding a 57,292-square-foot residential building, with 35 to 50 living units, on the parking lot at the site, which is between Cowper and Webster streets.

In pitching the mixed-use project, the developer requested changing the zoning designation from "planned community" to "downtown commercial" (CD-C (P)). Rob Zirkle, project architect, said that the idea behind the proposal was to support the concept of "sustainable cities" by including both jobs and housing. And in considering how much housing to add to this downtown location, the developer thought it would make sense to go for more, given the city's well-documented housing shortage.

"It seemed like a better idea to focus energy on housing than to pull housing away," Zirkle said.

Though the proposal remains in a conceptual state, with no application filed, it has been generating heated opposition around downtown and beyond. Many objected to the size and density of the proposed development. Others objected to the idea of adding more office space to downtown. Yet others questioned the wisdom of removing the existing building, which was constructed in 1971 and is currently occupied primarily by psychologists, psychiatrists and other mental-health professionals.

In recent weeks, residents and employees of the existing office building bombarded the council with protest letters to complain about a project that many deemed far too massive and disruptive for an area where parking and traffic concerns are already generating considerable anxiety. About 50 opponents also attended the Monday hearing, with many of them wearing "Save 550 Hamilton" buttons.

Jacob Towery, a psychiatrist who works at the building, said he regularly sees local high school students suffering from depression, anxiety, post-traumatic stress disorder and other serious mental-health issues. If the building were demolished, many mental-health professionals would end up leaving town, forcing patients to find new doctors or make longer trips to get the needed help.

Nancy Ginsburg, another psychologist who works at the building, made a similar point.

"If this project goes forward in any size or form, it will have a very negative effect on mental-health services in Palo Alto and the surrounding area," she said.

Others opposed the building's mass, density and potential traffic impacts. Some said they don't believe the new building would be compatible with the single-family homes on Webster Street.

Suzanne and Bruce Cocker, who live on Hamilton Avenue, urged the council to halt the project before it gets any further in the development process.

"Let's just stop this now," they wrote in an email to the council. "We are generally supportive of business and commerce but the City of Palo Alto is going through a period of apparently unrestrained development. It is time to take a pause and see where we are before considering another major project -- and it is not in anyone's interest to string the developers along."

The Monday meeting was a "prescreening," a type of hearing where the council offers early feedback to the applicant but takes no formal action. But given the surge of opposition and the general sentiment among council members that downtown office growth should be curtailed, rather than encouraged, the message from the council was clear: the project, as proposed, isn't getting anywhere.

While some council members said they were open to more housing, the idea of adding a larger office building to replace an existing one found no traction.

Mayor Pat Burt said he was surprised that the applicant even proposed it, given the council's recent moves to curtail office growth. These include placing an effective moratorium on "planned-community" projects, where developers barter with the City Council over entitlements and "public benefits"; and implementing an annual office cap of 50,000 square feet for new office space in the city's main commercial areas.

Burt acknowledged that some of the design features of the proposed project might be more favorable in some ways than in the existing building. Yet he also noted that by adding more office workers, the project would do little to diminish the city's jobs-to-housing imbalance, which is currently estimated at about 3 to 1.

"We don't attain anything in the jobs-housing imbalance," Burt said. "We just add more office and more housing."

His colleagues agreed that the project, as presented, has little chance of advancing. Councilman Tom DuBois said he's never gotten as many emails to oppose a project as in this case. The community's reaction to this proposal, he observed, was "pretty extreme."

Councilman Eric Filseth concurred and said that he generally opposes replacing existing buildings with larger ones unless there is a "clear reason to do so."

"One of the risks of putting up oversized -- relative with neighborhood surroundings -- buildings is that it makes it easier to build the next one," Filseth said.

Toward the end of the hearing, Councilwoman Liz Kniss summarized the overwhelming sentiment when she said that the proposal "does not have a great deal of legs."

"The developer really needs to know: Is there any appetite for this?" Kniss said. "I'm not hearing that tonight. And I think it's important that we deliver that in a straightforward way."