OAKLAND -- The Oakland Zoo's Measure A1 parcel tax -- one of the fiercest battles on the Nov. 6 ballot -- appears to have come up short of the two-thirds majority needed to pass.

The measure, which finished with 63 percent of the vote, was supposed to generate $112 million over a 25-year span to pay for the basic needs and care of zoo animals, facility upgrades, staff, education programs and field trips.

To raise the money, residential properties would be taxed $12 per parcel and $72 per nonresidential parcel. The tax would appear on 2013-14 property tax bills.

The Alameda County Registrar's Office said Wednesday morning that it was still counting late mail-in ballots that aren't reflected in the totals.

The East Bay Zoological Society, which manages the zoo, has issued dire warnings that without the revenue from the tax the zoo faces a perilous future.

The Friends of Knowland Park and No on Measure A1 argue the zoo could use the tax revenue as an "open checkbook" to support an expansion of zoo grounds, which the group has tried unsuccessfully to block in court for environmental reasons.

And the language of the measure would allow the zoo to use the money for operations to enable the expansion.

Opponents went after zoo officials for campaign violations.

As a result, the Oakland city attorney ordered the zoo to remove pro-Measure A1 signs from the grounds because the land is off-limits to campaigning.

But the zoo so far has fought off allegations that officials are mingling campaign and public money together.