Lawyers supporting the proposed settlement said that they prefer to have an agreement with Purdue rather than face the uncertainty of protracted litigation with no guarantee of a better outcome.

Paul Geller, a plaintiffs’ lawyer working to resolve the federal cases, said: “Nobody walks away from a difficult negotiation feeling like a winner. But one thing was certain during difficult, protracted negotiations — a bankruptcy filing by Purdue was inevitable.”

Herbert Slatery, the Tennessee attorney general, called the deal a significant step to “obtain meaningful relief to address the opioid crisis.”

The plan, Mr. Slatery said, “would secure billions of dollars nationwide to go toward addressing the devastating effects of the opioid epidemic and will result in the Sackler family divesting themselves of their business interests in the pharmaceutical industry forever.”

But because the tentative agreement falls short of what some state attorneys general were seeking, they have said that they will continue to pursue the Sacklers. In recent weeks, perhaps in anticipation of legal fortresses built by the Sacklers to guard their fortune, which Forbes estimated to be about $13 billion, more states, including Virginia, New Mexico and Delaware, filed cases against members of the family. States have used an array of legal tactics, hoping to win an even bigger payout from the Sacklers and to force them out of the pharmaceutical business altogether.

A critical sticking point has been the timing of the family’s sale of its global pharmaceutical business, Mundipharma, and the contribution the family would make from the proceeds. Some attorneys general, including those from Massachusetts, New York, New Jersey, Pennsylvania and Connecticut, who have not signed on to the settlement, had been pressing the family to sell Mundipharma immediately and to discontinue manufacturing drugs for international markets. In addition, the attorneys general said, they wanted the Sacklers to commit an additional $1.5 billion up front.

The family rejected those terms.

The attorneys general for several states vowed to push on. Letitia James, New York’s attorney general, called the deal “an insult, plain and simple.”