An oversight board put Nassau lawmakers on notice Thursday night over a potential 2017 county budget deficit of up to $217 million.

That would cause the county to be "fiscally challenged" next year, according to the Nassau Interim Finance Authority, the board that oversees the county's finances.

As a result, NIFA unanimously passed a resolution to reject any budget proposal that features a deficit exceeding $60 million.

"We want to see a reduction in the deficit going forward, and we've basically given the county a number that they have to reach in order to achieve a budget that we will approve," said Adam Barsky, the NIFA chairman.

NIFA said County Executive Ed Mangano's budget proposal features several risks. The board is concerned that projections from sources of income like the county's Off-Track Betting and the sale of county property may be overly optimistic. 

The NIFA report added that Mangano's proposal to increase fees and fines in an effort to raise $88 million in new revenue would go a long way to eliminating much of the projected shortfall, but legislative Democrats have vowed to fight the fee hikes. 

Opponents call the increased fees a "back door" tax. Legislator Carrie Solages said the county should instead install an inspector general to cut down on corruption.

Solages countered by calling for a deficit cap of closer to $100 million.

Barsky said the control board will address the projected budget shortfall on its own if lawmakers could not come to an agreement.

"The last thing [we] really want to do is go in and make the budget cuts ourselves, which I don't think anyone would be happy about," Barsky said.