The Cambridge City Council postponed a vote on a proposal to make Harvard Square a historic district Monday, saying that the proposal did not have enough support for approval.

A committee will now look into the idea of making the Square a conservation district instead, which would not give the same level of protection to historic buildings that an historic district would.

"Historic district are established under general laws which are very strict about what things have to be reviewed," said Charles M. Sullivan, executive director of the Cambridge Historical Commission.

Creating an historic district would give the a commission "binding review over demolition, new construction, and publicly visible exterior alterations to existing buildings."

According to Sullivan, conservation districts can be "tailored to the particular needs of a neighborhood," and do not establish the same binding review procedures as an historic district.

Another major distinction between historic districts and conservation districts involves the rights of non-profit organizations.

Under historic districts, non-profits groups--such as the Harvard Square Defense Fund--have legal standing to appeal decisions made about the historic district.

"There is concern in Harvard Square because there has been so much litigation in the last 25 years," Sullivan said.

Conservation districts do not give automatic standing to non-profit groups to appeal decisions, making it more likely to be approved by the council.

There are currently three conservation districts in Cambridge--in Mid- Cambridge, Half Crown and Avon Hill.

Councilor David P. Maher said the re-wording was necessary because a historic district did not appear to have the needed votes for approval.

"There was a feeling that there was not the support for an historic district, and before shelving the entire proposal, they would take a look at this aspect of it, and report back," Maher said.

But the re-filing confused councilor Kenneth E. Reeves '72, who said not enough was known about the idea of a conservation district to consider the idea. He criticized City Manager Robert W. Healy, who he said was unable to answer questions about the matter.

"What is this all about?" Reeves said. "We had a proposal for an historic district. We could have voted on it. We're apparently not voting. Now there's this apparent ghost of the neighborhood conservation possibility."

"It's unclear to me what it is, and with the responses given here, it seems to be a mystery to the city manager too," he added.

Tensions flared when Councilor Michael A. Sullivan immediately responded to Reeves' question, saying the matter was discussed at a poorly attended ordinance committee meeting with Charles Sullivan.

"I was there," Reeves answered back. "I wasn't there the whole time."

The council finally voted to re-file the item, which has been on the unfinished business agenda since January.

It will likely not come back before the council--which goes on a six-week vacation this summer--for several months.

Some councilors praised extending the study of proposals for Harvard Square, saying they need more time to consider all possibilities.

"This extension of several months is prudent and it will yield us a well elucidated choice when it comes to us in a few months," councilor Kathleen L. Born said.

And the Historic Commission's Sullivan says that an historic district is "still on the table."

Reeves said he still held doubts about the need to re-file the petition.

"If people weren't going to vote for the last [proposal], I don't know how they would vote for the other one," he said. "I don't want to waste citizen time."

Dut to lengthy public comment and council discussion, the meeting lasted several hours longer than usual.

Vice Mayor Maher had to chair the meeting for a brief period while Mayor Anthony D. Galluccio attended an awards ceremony for a high school mentoring program. He returned during the council's recess before 9 p.m., but the meeting lasted past midnight.