The Puerto Rican Senate approved the measure at about 3 a.m. Tuesday. The House, after becoming embroiled in a dispute over whether certain types of bonds should be excluded, approved it around 1 a.m. Wednesday.

Stephen Spencer, who represents some investors who have already agreed to restructure their bonds, said, “We intend to carefully review the legislation, but at this stage we believe that it may lead to violations of the terms of the agreement.”

He said that the administration last fall had hailed that restructuring as a model for others to follow, adding that the bondholders he represents should have been excluded from any coming moratorium, “rather than being cast into a state of uncertainty.”

The bill did not specify a starting date for a moratorium, leaving that decision to the governor. But a big debt payment, $422 million, is due on May 1, and there have been many signs that Puerto Rico is not able or willing to pay it.

That payment is due on bonds issued by the Government Development Bank, an institution that plays a critical role in the island’s financial affairs, including holding deposits of municipalities and other government entities. As recently as last week, holders of the bank’s debt were in talks about an agreement that would give the bank some breathing room if it failed to make the payment.