SAN FRANCISCO (AP) _ Two ballot measures that could let the city seize transmission lines and plants and provide energy through a public power agency were virtually deadlocked Wednesday, but thousands of ballots remained uncounted.

Proposition F would allow an elected board to buy Pacific Gas & Electric Co. infrastructure, as well as transform the city utilities commission into a department of water and power.

Measure I would create an independent municipal utility district representing San Francisco and nearby Brisbane with an elected board. It also could buy PG&E power plants and transmission lines.

Thousands of ballots that arrived in the mail Tuesday were isolated so election officials could ensure they were not tainted with anthrax. The city had not received any threats, but was trying to take precautions, Department of Elections Director Tammy Haygood said Wednesday.

Backers of the propositions complained Wednesday that it appeared the isolated ballots were left at least partly unguarded for about two hours Tuesday. They said a sheriff's deputy left the ballots at about 10 p.m.

Two hours later, reporters saw a lone private security guard standing watch.

Haygood said the ballots had not been left alone. She asked at midnight that sheriff's deputies return.

Proposition F was passing Wednesday with 56,668 votes in support of the measure to 54,727 votes against it, a 51-49 percent margin. Measure I, was losing by the same 49-51 percent margin, with 53,136 votes for and 54,835 against.

No matter the outcome, opponents of public power said the totals showed the measures lacked overwhelming support.

``It's certainly not a mandate for any kind of new public power agency or city government utility at this point, no matter which way the election turns out,'' said Jon Kaufman, a strategist for the ``No on F&I'' campaign.