Joseph R. Biden Jr. forcefully defended Social Security in a speech to disability advocates in Chicago on Tuesday, condemning the Trump administration for “taking a hatchet” to the Social Security Administration.

In his first expansive public comments since leaving the White House, Mr. Biden said that President Trump had taken aim at Social Security, doing “damage and destruction” to a program that millions of Americans depend on.

“Social Security deserves to be protected for the good of the nation as a whole,” Mr. Biden said, adding that Trump officials are applying a Silicon Valley mantra of “move fast and break things” to the government. “Well, they’re certainly breaking things. They’re shooting first and aiming later.”

Mr. Trump has promised not to cut Social Security benefits for the 73 million Americans enrolled, but offices around the country have been flooded with calls and questions from Americans who are worried that changes to their benefits and to their local Social Security offices may be imminent.

At local offices, many staff members have taken buyouts or early retirements promoted by the Trump administration’s cost-cutting efforts, leading to longer phone waits and lines. The Social Security Administration has said it wants to shed thousands of jobs at its headquarters.

Mr. Biden said that during his own administration, the Social Security Administration cut wait times, improved antifraud measures and made the appeals system for benefits more uniform.