In addition, the governors announced support for a bill that would apply the Freedom of Information Law to the authority, pending some minor modifications.

In a statement, Mr. Cuomo said the changes would “address the Port’s inefficient and outdated governing structure and will help bring new transparency and effectiveness to the agency.” Mr. Christie echoed those remarks, saying that he and Mr. Cuomo “remained advocates for reform at the Port Authority and are encouraged by these recommendations from the bistate panel.”

But legislators said the governors’ recommendations lacked the sweeping and forceful changes of law that were needed to overhaul the agency, and would simply delay the reforms. “The process will have to start all over from scratch,” said Senator Robert M. Gordon, a Bergen County Democrat who sponsored the bill. “I’m at a loss.”

And though Mr. Gordon said he was grateful that the governors had embraced — in spirit, at least — some of the proposals, he said he was perplexed and disappointed by the veto, which he believed would set back the lawmaking reforms by at least a year.

Other supporters, who had hoped the unanimous votes in the states’ Legislatures would convince the governors to accept the changes, said the authority had lagged behind many other New York entities in accepting somewhat commonplace ethical standards.

“It is a cynical thing that they would announce their own panel’s reforms while simultaneously vetoing a proposed law that would simply apply existing ethical standards,” said Assemblyman James F. Brennan of Brooklyn, a sponsor of the bill.

In recent days, backers of the legislation had become increasingly nervous about it as dual deadlines for Mr. Cuomo, who had to act by Sunday morning, and Mr. Christie approached and neither man showed enthusiasm for the bills. But the veto struck even veterans of Albany politics as exceedingly opaque.