After 21 weeks of unsuccessful budget negotiations, the PA State Senate has brought up a debate over who pays for public schools, threatening to destroy any framework of a deal.

Education funding and school property taxes have proved to be the key sticking points for the last few weeks as Gov. Tom Wolf and GOP leaders try to thrash out a deal. Now, the state’s upper chamber will look at the complete elimination of property taxes, the “preferred option” of some lawmakers, Marc Levy of the Associated Press reports.

The Senate is expected to vote Monday on the bill that could bring “perhaps the biggest-ever change in state taxation,” Levy reports. If passed, voters would be required to approve any future tax increase.

On Saturday night, House Democrats began looking at a new way forward, after hearing there would not be enough GOP support to push through an agreement between Wolf and Republican leaders.

The agreement was slated to raise the state sales tax by 1.25%, while raising $400 million in additional education funding. $600 million in slot-machine revenue would have been diverted to the state treasury.

A spokesman for House Majority Leader Dave Reed told reporters on Sunday morning that the deal was not completely off, depending on how property tax rebates are distributed.

Reed was optimistic at the beginning of the month when he told fellow Republicans he was confident of a deal by Thanksgiving. With the latest developments, a deal by New Year’s even seems hopeful.