The Baker administration "just can't wait" for lawmakers to take up a spending bill and will instead tap into already-available funds to help manage a ballooning emergency shelter crisis, a top official said Tuesday.

Top Democrats have not outlined any plans for acting on the $139 million supplemental budget Gov. Charlie Baker filed Nov. 18, which he said would deploy key resources needed to respond to a "humanitarian crisis" fueled in part by an influx of migrants arriving in Massachusetts.

While the administration will ultimately need legislative authorization, Administration and Finance Undersecretary Catharine Hornby said the executive branch will make use of some funds already available to kickstart some of the action sought with the supplemental budget, including the launch of a new intake center in Devens and expansion of emergency shelter capacity.

An economic development bill Baker signed into law last month included a $20 million allocation to address immigrant and refugee needs.

"We've come to the conclusion that we just can't wait, that we're going to need to figure this out," Hornby said at a Local Government Advisory Commission meeting. "There are certain things that we're going to just do. But when it comes to schools, we don't have the authorization. We need this bill to proceed through the Legislature."

The budget Baker filed would steer $73 million toward expanding the shelter system's capacity, make $20 million available for the temporary intake center, and use $37 million to help manage the costs of placing new students in schools.

Officials did not say Tuesday how long they will be able to run the Devens intake center, which will open some time this month, without legislative action on that bill.