IF THEY FAIL to reach a compromise before Wednesday afternoon, leaders of the House and Senate will lose out on tens of millions of dollars in budgetary allowances that have quietly accumulated for their chambers over the years.

That could add some urgency to negotiations that have already entered their final hours.

At loggerheads over the particulars of the closeout spending bill, the House and Senate have blown past deadlines for closing the books on fiscal 2019. They are now heading toward a scenario where some accounts remain in deficit for fiscal 2019, and where the House and Senate forgo more than $33 million in funding they have salted away for the two chambers over the years.

Their last chance to avoid that outcome is by enacting a closeout budget bill that is then approved by Gov. Charlie Baker before 3 p.m. on Wednesday, Comptroller Andrew Maylor warned in a letter earlier this month. The letter specifically says that “continuing appropriations” would not be funded if the closeout budget isn’t enacted by that time.

In the case of the House, that amounts to more than $25 million, according to data maintained by the comptroller’s office. In the Senate there is about $8 million that would be washed into the state’s reserve fund unless an agreement is reached. The governor and lieutenant governor’s offices have about $1 million on the line. There was also about $3 million for joint legislative operations that was not spent in fiscal 2019.

A spokesperson for Maylor and an official in the office of Senate President Karen Spilka each confirmed that without finalized legislation closing the books on fiscal 2019, those rollover accounts would essentially be dumped into the stabilization fund. House Speaker Robert DeLeo’s office did not respond to inquiries about the roll-over funding.

There is also some mystery about what the House and Senate might be saving up for. The Senate recently completed renovations to its historic chamber that cost about $22.6 million. DeLeo has previously discussed hoping to do the same for the House chamber, which has crumbling walls, shabby carpet, and voting equipment that occasionally malfunctions. An extra $25 million could be of use to the House when it finally moves forward on chamber renovations.

As important as it is, the specific reasons why the House and Senate can’t agree on a closeout budget are shrouded from public view. Spilka said it is “not about spending,” according to the State House News Service. DeLeo has floated the idea of passing a bare-bones bill that only funds accounts that ended fiscal 2019 in deficiency. One of the biggest differences between the House and Senate versions of the closeout legislation was the House’s inclusion of tax relief that would be available for certain corporations.

In addition to allowing the House and Senate to roll over millions in appropriations and prevent accounts such as snow and ice cleanup to remain in deficit, the closeout budget could potentially include spending in some other areas as well. Baker has suggested $50 million for the MBTA and millions of dollars for water testing would be essential elements to any compromise legislation. If the House and Senate do reach agreement in time, a possibility that grows less and less likely by the hour, Baker will have line-item veto authority, and the House and Senate will have no recourse to reverse any of the governor’s potential vetoes.