Just in from the Associated Press:

The United Auto Workers union says it has reached a tentative agreement on contract concessions with the U.S. government and General Motors Corp., a key step toward GM's effort to restructure out of bankruptcy court.

The union has this notice posted on its website:

The UAW has reached a tentative understanding with the U.S. Treasury and General Motors on an addendum to the 2007 UAW GM collective bargaining agreement. The tentative understanding contains modifications to the labor agreement and to the independent Voluntary Employee Beneficiary Association (VEBA) trust.

Details are being withheld pending explanation and ratification meetings for UAW GM members, which are in the process of being scheduled.

The Detroit Free Press adds that the deal "is an important step as GM works to restructure while operating on a government loan. It also must restructure its debt by June 1, and Chapter 11 bankruptcy reorganization is seen as highly likely for the giant automaker."

Update at 1:15 p.m. ET. NPR's Frank Langfitt reports that:

Union officials agreed to changes in labor costs and company contributions to a retiree health care trust fund.

But UAW leaders would not disclose details before taking the changes to workers for a vote.

By itself, a deal would not prevent a bankruptcy — which many observers see as inevitable. But it would help a bankruptcy proceeding go more quickly, which GM says is critical to its survival.

The company still has to cut deals with bondholders to whom it owes $27 billion dollars.

The White House has given GM until the end of this month to radically restructure or
file for protection under Chapt. 11 of the bankruptcy code.