And many of the surveillance programs exposed by Edward J. Snowden, the former National Security Agency contractor now living in exile in Russia, remain in place, as does an enormous apparatus built up in the last 14 years in the name of defending the United States against attack.

Still, for supporters of Russ Feingold, the Wisconsin Democrat and lone vote against the Patriot Act in the Senate in 2001, the alterations heading for likely approval in Congress are a long overdue vindication and correction.

“There was frankly an overreaction, and now over time and space, the American people are trying to figure out, O.K., what are the genuine threats there and what’s the best way to use our resources and power?” said Farhana Khera, a former aide to Mr. Feingold and now president of Muslim Advocates, a legal organization.

“Hopefully,” she added, “we’re starting to see some sanity come back into the discourse.”

Peter Swire, a Georgia Tech professor who has studied these issues for years, said the import of the new legislation went beyond the specific legal changes. “This is more than symbolic,” said Mr. Swire, who also served on Mr. Obama’s task force. “Congress is saying to stop bulk collection on Americans. That makes any future agency lawyer think twice or three times before authorizing a mass collection program.”

But some of those who supported broader surveillance in the past said Americans should remember the reasons it had been initiated. “If you were there at ground zero or went to the Pentagon, you’d never want to experience that again,” said former Representative Pete Hoekstra, a Michigan Republican who was chairman of the House Intelligence Committee.

The real overreaction, he said, has been to the disclosure of the programs by Mr. Snowden, which he said had not resulted in reports of widespread abuse. The government was collecting data about phone calls, he noted, not listening in on the conversations of Americans without warrants. “I don’t think you could find one-third of Americans who understand what this does,” he said.