House lawmakers were set to gavel in Saturday morning for their third session in as many days to consider a nearly $3.1 billion supplemental budget that includes money for union contracts and the state’s emergency shelter system after Massachusetts Republicans blocked its path forward twice.

Democrats and Republicans have pointed fingers at each other over who is at fault on Beacon Hill for delaying funding for 95 union contracts, which include raises for tens of thousands of public sector employees just ahead of the holidays.

But some unions are clearly taking sides. In a blistering statement Friday afternoon, the Massachusetts AFL-CIO said it was “astonished and appalled” that the budget bill was not passed Friday.

“The inaction and continued obstruction by a small group of House Republicans makes it increasingly more likely that 60,000 public sector employees will not see their collectively bargained raises in time for the holidays and colder weather,” the organization said.

House and Senate Republicans have said they are concerned with $250 million for the state’s struggling emergency shelter system, which has been pushed to its limits by a surge of new migrant arrivals and crushing housing costs in Massachusetts.

“My caucus continues to have a concern over the migrant issue, We’re spending $250-plus million dollars on top of what’s already been appropriated, and every single indication is that the governor of the Commonwealth is going to file a new request, either at the end of this year or in January, looking for additional resources to deal with that issue.”

The small minority gained the power to block the proposal when Democrats failed to pass it in formal sessions, where lawmakers can offer debate, take recorded votes, and Democrats have an overwhelming supermajority.

Formal law making came to a close more than two weeks ago and consideration of the bill was kicked into informal sessions, where any one legislator can halt a bill’s path forward using procedural tactics.

Republicans blocked the budget bill from moving forward Thursday and Friday.

House Speaker Ronald Mariano has blasted Republicans for putting up a blockade while Republicans have called on the Quincy Democrat to reconvene the House in a formal session so lawmakers can once again debate the proposal.

“It’s incredibly disappointing that House Republicans are blocking the passage of the supplemental budget. This bill includes $3 billion worth of critical funding for state employee raises and for a number of other pressing issues,” he said in a statement. “Despite that, House Republicans are willing to jeopardize the entire package over $250 million that will be used to provide shelter for all vulnerable families in Massachusetts.”

The House plans to gavel into session at 11 a.m. Saturday in a mostly empty State House.

Massachusetts Teachers Association President Max Page and Vice President Deb McCarthy also criticized the Legislature’s “inability to pass a budget that addresses the plight of families in need of shelter, as well as funds long-ratified contracts for state workers” as a “stunning failure.”

“More than 50,000 unionized employees responsible for human services, health care, higher education and other endeavors dedicated to the common good of our state are waiting on pay raises their families are counting on, especially as we head into the winter months and holiday season,” the pair said in a statement.

This is a developing story…