Cook County Board President Toni Preckwinkle is gearing up for a vote on her 2012 budget on Friday, even though the county still has not struck a deal with labor unions to avert nearly 800 layoffs.

Preckwinkle’s administration estimates the layoffs will save $40 million next year, at a time when the county is looking to close a $315 million deficit. She has said union workers could avoid about 500 of the layoffs if they agree to take unpaid holidays.

But as of Friday morning, Preckwinkle said there was still no agreementdespite ongoing talks.

“We came to an agreement with our unions in the middle of the night … in the last budget cycle,” Preckwinkle said, referring to the 2011 budget process that dragged on right until the legal deadline. “And I can’t predict what’s gonna happen this time.”

Commissioners on Friday shot down a proposed penny-a-pack cigarette tax hike, and a new tax on cigarette rolling machines - both measures that had been pushed by the American Federation of State, County and Municipal Employees, or AFSCME, the union that represents about 5,000 county workers.

Labor unions have also suggested that Preckwinkle should dip into reserve funds in order to avoid layoffs. But the county’s rainy day fund is already at a perilously low level, and any withdrawal could trigger a downgrade from credit agencies, which would result in higher borrowing costs for the county, Preckwinkle said.

Though the impasse between Preckwinkle and unions continues, her 2012 budget has already cleared some key hurdles and seems likely to pass a final vote Friday. Earlier this week, commissioners signed off on some key revenue-generating proposals that the president is hoping will bring at least $48 million to the county next year. Those include a hike in the alcohol tax, and the tobacco tax expansion.

Republican Commissioner Peter Silvestri said he expects to cast a “yes” vote Friday. He came out against the president’s call for more tobacco taxes, but got behind a small hike in alcohol taxes.

“I don’t think people are gonna leave their favorite watering holes, so to speak, to go to Indiana or DuPage to have a drink,” he said.

Preckwinkle, a Democrat, has won praise from commissioners after backing away from some unpopular budget proposals, such as a plan to charge courthouse parking fees for jurors, and an idea to make residents of unincorporated Cook County pay for police patrols from the county sheriff.

Following an era of often-contentious debates under former Board President Todd Stroger, Preckwinkle’s  flexibility caught Commissioner Tim Schneider, a Republican, a bit by surprise.

“What I never thought I would say, five, six years ago, is that Cook County could be a model for what other government agencies may look to for how government should be run,” Schneider said.