Two important votes concerning San Francisco's plan for citywide Wi-Fi that were set for this week have been pushed back, delaying what may be life-or-death decisions on the controversial network.

One vote of the city's fractious Board of Supervisors could force the project to undergo an environmental impact study. The other, by the board's Budget and Finance Committee, would reject the plan or send it on to the full body for final approval. Hanging in the balance is a proposal that was introduced by Mayor Gavin Newsom in 2004 and has become one of the major initiatives of his administration.

As the votes were pushed back, Board President Aaron Peskin was preparing a set of amendments to the contract hammered out by the city and EarthLink in January. Those changes aim to address concerns of some critics but may not win over vocal opponents on the board.

San Francisco is one of many municipalities pursuing wireless networks to make Internet access more widely available, both to close the technology gap between richer and poorer residents and to boost the local economy. Its contract calls for EarthLink to offer 1Mbps service for about $20 per month and Google to offer a free service on the same network.

Activists and some leaders in the city have raised alarms that echo worries in some other cities, such as how well the network will perform. They have also raised issues that are specific to San Francisco. For example, Google's proposed free service has come under particular fire for allegedly threatening users' privacy and being too slow, at 300Kbps.

In one local twist, the San Francisco Neighborhood Antenna-Free Union (SNAFU) has appealed an April decision of the city's Planning Commission that exempted the network from environmental review. SNAFU, which has fought the placement of cellular base stations near schools, hospitals and some other sites, says Wi-Fi access points on light poles could harm residents' health. It will be up to the Board to force the review or let the exemption stand.

At a pro-Wi-Fi rally outside City Hall on Tuesday, Newsom and other speakers called for quick approval of the project and scoffed at the environmental concerns.

Newsom called the environmental question "a canard." Citywide Wi-Fi is critical to minority communities that lack Internet access and is being fought mostly by people who have it, speakers at the rally said.

Leslie Rule, an educational technologist at local public broadcaster KQED, said she had read all of SNAFU's appeal of the Planning Department's decision. "They're worried about things that don't exist," she said.

The rally brought together multiple groups from minority communities and drew about 100 protestors waving "Wi-Fi Now" signs.

Peskin's proposed amendments, not yet spelled out in detail, include contract terms that would force EarthLink to serve all parts of the city and would boost the speed of the Google service to 500Kbps and protect users' privacy. They also would limit the term of network deal, under which the city would lease its light poles to EarthLink for placement of radios, to eight years and give the city the right to then buy the network.

In general, the proposals are things the city tried to get during its own negotiations with EarthLink, said Brian Roberts, a senior policy analyst at the city's Department of Telecommunications & Information Services, which negotiated the deal with EarthLink. The city chose to try to conclude the talks and get the network built rather than press for every term it wanted, he said.

"If Supervisor Peskin can get them, God bless him," Roberts said.

Peskin said via e-mail on Tuesday that EarthLink had not yet responded to the proposed changes. If Peskin can work out terms he likes with EarthLink, the contract is likely to pass through the Budget and Finance Committee, on which he serves. But on the full board, some long-time opponents question the amendments and other members are also waiting to see more details.