HARRISBURG — Pennsylvania lawmakers were headed toward an unusual weekend session in the Capitol without an agreement Friday on how to finance a $31.5 billion spending plan that has an uncertain future on the desk of Democratic Gov. Tom Wolf.

Rank-and-file House representatives said Friday that they did not know what they will be asked to vote for during Sunday’s session. They also said they had been informed that there remained no agreement after weeks of discussion between Wolf and top lawmakers on a revenue package that was expected to include a tax increase on cigarettes.

“We’re coming back Sunday, we’re sorting out a couple details and hopefully we’ll have it signed, sealed and delivered by Tuesday,” said Rep. Kerry Benninghoff, R-Centre.

The Senate had no plans to return until at least Monday.

The struggle over how to shore up Pennsylvania’s deficit-ridden finances has left it as the only state government without an enacted budget for part or all of the new 2016-17 fiscal year.

Lawmakers are up against a midnight Monday deadline for Wolf to decide how to handle a roughly $31 billion spending bill on his desk before it becomes law without his signature. He has said that he would not sign it without sustainable revenue to pay for it.

Meanwhile, legislation authorizing another nearly $600 million for Penn State, Pitt, Temple, Lincoln and Penn remains in limbo in the House and legislative staff aides were preparing hundreds of pages of budget-related bills.

Budget negotiators remained tight-lipped about how they would raise the more than $1 billion that they say is necessary to balance $31.5 billion in spending. They maintained that they were close to an agreement.