JUNEAU — Alaska's already massive budget deficit has jumped another $300 million thanks to low oil prices, Gov. Bill Walker's administration said Monday.

The state's unrestricted revenue forecast for the current fiscal year, which ends June 30, dropped to $1.3 billion from an earlier projection of $1.6 billion, according to a new preliminary forecast by the revenue department released Monday morning. The exact drop is about 17 percent, the department said, and it's based on sustained low oil prices.

The revised forecast means the expected deficit for the state's $5.4 billion budget is now $4.1 billion, up from a previously projected $3.8 billion. That means current revenue can cover only about 25 percent of the existing state budget.

The picture for the following year is even worse, with the forecast revised downward to $1.2 billion from a previous $1.8 billion projection.

Walker, in a news conference at the Capitol on Monday, said the diminished flow of oil revenue underscores the need for lawmakers to pass his financial plan.

Under the plan, the state would pay for government largely based on an annual $3.3 billion stream of revenue from a restructured Alaska Permanent Fund, instead of from oil revenue. Alaska's oil revenues have crashed as prices dropped to $39 a barrel last week from more than $100 two years ago.

"We have reached a point in our state's history that we need to be looking beyond oil a bit," Walker said. "We have that opportunity now. And you're not going to do it by sitting back with a Ouija board hoping the price of oil's going to go to $110, $147. It just isn't going to work."

Three-fourths of the state's unrestricted revenue last year came from petroleum revenue, which Alaska has relied on for decades to pay for state government and services. But the price predictions that the Walker administration used to make its preliminary 2016 and 2017 forecasts were overly optimistic.

The previous 2016 forecast called for oil prices at $50 a barrel — and $56 in 2017. The state's new prediction calls for oil to stay at $40 a barrel in 2016 and $39 in 2017.

The change wipes out 26.5 percent of the state's unrestricted revenue from oil and gas this year.

Since the state's forecast two years ago, projected oil prices for 2016 have dropped 63 percent, down from $108 per barrel.

"It's all about lower prices," Revenue Commissioner Randy Hoffbeck said in a prepared statement.

Lawmakers are debating Walker's proposals to close the budget gap, which, in addition to the proposed Permanent Fund restructuring, include a personal income tax and increased taxes on consumption and resource extraction.

Monday's report is a preliminary version of the annual spring revenue forecast. Last year's spring revenue forecast was released in early April, but the Walker administration released a preliminary version this year "to aid in the budget discussions," Hoffbeck said in the statement.?