WASHINGTON — Giants in telecommunications, like Verizon and AT&T, will not have to take “reasonable measures” to ensure that their customers’ Social Security numbers, web browsing history and other personal information are not stolen or accidentally released.

Wall Street banks like Goldman Sachs and JPMorgan Chase will not be punished, at least for now, for not collecting extra money from customers to cover potential losses from certain kinds of high-risk trades that helped unleash the 2008 financial crisis.

And Social Security Administration data will no longer be used to try to block individuals with disabling mental health issues from buying handguns, nor will hunters be banned from using lead-based bullets, which can accidentally poison wildlife, on 150 million acres of federal lands.

These are just a few of the more than 90 regulations that federal agencies and the Republican-controlled Congress have delayed, suspended or reversed in the month and a half since President Trump took office, according to a tally by The New York Times.

The emerging effort — dozens more rules could be eliminated in the coming weeks — is one of the most significant shifts in regulatory policy in recent decades. It is the leading edge of what Stephen K. Bannon, Mr. Trump’s chief strategist, described late last month as “the deconstruction of the administrative state.”

In many cases, records show that the changes came after appeals by corporate lobbyists and trade association executives, who see a potentially historic opportunity to lower compliance costs and drive up profits. Slashing regulations, they argue, will unleash economic growth.

On a near daily basis, regulated industries are now sending in specific requests to the Trump administration for more rollbacks, including recent appeals from 17 automakers to rescind an agreement to increase mileage standards for their fleets, and another from pharmaceutical industry figures to reverse a new rule that tightens scrutiny over the marketing of prescription drugs for unapproved uses. As of late Friday, word had leaked that the automakers’ request for a rollback was about to be granted, too.

“After a relentless, eight-year regulatory onslaught that loaded unprecedented burdens on businesses and the economy, relief is finally on the way,” Thomas J. Donohue, the president of the United States Chamber of Commerce, wrote in a memo last week.

But dozens of public interest groups — environmentalists, labor unions, consumer watchdogs — have weighed in on the potential threat to Americans’ well-being. “Americans did not vote to be exposed to more health, safety, environmental and financial dangers,” said one letter, signed by leaders of 137 nonprofit groups to the White House last week.

In other cases, the Obama-era rules under attack have drawn objections even from some liberal groups that called them examples of overreach, like the American Civil Liberties Union’s protest of a system to block mentally ill people from buying guns.

The regulatory retrenchment is unfolding on multiple fronts.

Congress, with Mr. Trump’s approval, has erased three Obama-era rules in the last month, lifting regulations related to coal mining and oil and gas exploration, as well as the sale of guns to the mentally ill. More than 25 more rules could also be erased in the coming weeks; the House has already voted to eliminate nearly half.

Mr. Trump has separately signed executive orders directing agencies to pursue the reversal of other rules, including a requirement that financial advisers act in the interest of their clients, and a rule aimed at protecting drinking water from pollution.

New White House appointees at agencies including the Federal Communications Commission, the Securities and Exchange Commission, the Interior Department and the Environmental Protection Agency have also personally intervened in recent weeks to block, delay or start the process to nullify other rules, such as a requirement that corporations publish tallies comparing chief executive pay with average employee wages.

The Trump administration has also imposed a broad regulatory freeze, instructing agencies to delay the adoption of any rules not already in effect, and to consider whether those rules should be targeted for elimination.

And it has set up barriers to enact any new regulations — such as a requirement that for each new rule, at least two others must be identified for repeal — and ordered every federal agency to create a team of employees to look for more rules that can be eliminated.

“By any empirical measure, it is a level of activity that has never been seen,” said Curtis W. Copeland, who spent decades studying federal regulatory policy on behalf of Congress while at the Congressional Research Service and the Government Accountability Office. “It is unprecedented.”

Mr. Trump, in his address to Congress last week, called it “a historic effort to massively reduce job-crushing regulations,” a line that drew thunderous applause from Republicans.

Presidents wield considerable influence over the rule-making process. They set the agenda and appoint the rule-makers, and, since the Reagan administration, a White House office has reviewed every major regulation to try to ensure that benefits to society…