Former U.S. President Joe Biden speaks at the Advocates, Counselors, and Representatives for the Disabled conference on Tuesday in Chicago. The Associated Press

CHICAGO — Former President Joe Biden warned on Tuesday that President Donald Trump has “taken a hatchet” to Social Security, weighing in on a critical issue for millions of Americans as the 82-year-old Democrat briefly returned to the national stage.

Biden, who has largely avoided speaking publicly since leaving the White House in January, delivered his pointed message during an evening speech at the national conference of Advocates, Counselors and Representatives for the Disabled in Chicago. The former president, who was largely focused on his prepared remarks but rambled at moments, was speaking as Democrats across the nation offered similar warnings for what they described as a Social Security Day of Action.

“In fewer than 100 days, this new administration has done so much damage and so much destruction. It’s kind of breathtaking,” Biden charged during a speech that spanned just under a half hour. “They’ve taken a hatchet to the Social Security Administration.”

It was no coincidence that Tuesday’s appearance, which marked Biden’s first major speech since leaving office, was focused on Social Security. Democrats have increasingly focused on Trump’s turbulent leadership over the popular government agency that provides benefits to tens of millions of Americans.

Both parties expect Social Security to emerge as a key issue in next year’s midterm elections.

The appearance also marked the first time Biden has explicitly attacked Trump since becoming a private citizen, although Biden referred to the Republican president only as “this guy” on Tuesday. Trump, by contrast, continues to blame Biden for many of the nation’s problems and often attacks his predecessor by name.

White House press secretary Karoline Leavitt took a shot at the former president’s age when asked about his speech earlier in the day.

“I’m shocked that he is speaking at nighttime,” Leavitt said during Tuesday’s White House press briefing. “I thought his bedtime was much earlier than his speech tonight.”

She said that Trump, who is 78 years old, would sign a presidential memorandum Tuesday afternoon “aimed at stopping illegal aliens, and other ineligible people, from obtaining” Social Security benefits. The memorandum will expand the Social Security Administration’s fraud prosecutor program to at least 50 U.S. attorney offices, and establish Medicare and Medicaid fraud prosecution programs in 15 U.S. attorney offices, Leavitt said.

Despite such moves, the Social Security Administration has been plagued by controversy under Trump’s leadership.

The Republican president almost immediately began slashing the government workforce upon his return to the White House, including thousands of employees at the Social Security Administration.

Along with a planned layoff of 7,000 workers and contentious plans to impose tighter identity-proofing measures for recipients, the SSA has been sued over a decision to allow Trump adviser Elon Musk’s Department of Government Efficiency to access individuals’ Social Security numbers and other personally identifiable information.

Musk, the world’s richest man and one of Trump’s most influential advisers, has called Social Security “the biggest Ponzi scheme of all time.”

At the same time, Social Security recipients have complained about long call wait times as the agency’s “my Social Security” benefits portal has seen an increase in outages. Individuals who receive Supplemental Security Income, including disabled seniors and low-income adults and children, also reported receiving a notice that said they were “not receiving benefits.”

The agency said the notice was a mistake. And the White House has vowed that it would not cut Social Security benefits, saying any changes are intended to reduce waste and fraud.

Biden seized on the problems during his remarks.

“They’re shooting first and aiming later,” the former president said. “They want to wreck it so they can rob it. Why do they want to rob it? In order to give tax cuts to billionaires and big corporations.”