WASHINGTON -- Joe Biden, in his first major speech since leaving the White House, railed Tuesday against his successor Donald Trump's frenetic government overhaul, claiming the "hatchet" effort put Americans' retirement benefits at risk.

"Fewer than 100 days, this administration has done so much damage, and so much destruction -- it's kind of breathtaking it could happen that soon," Biden told a conference of disability advocates in Chicago.

"They've taken a hatchet to the Social Security administration, pushing 7,000 employees out the door," said the former president, referring to the national agency which pays out retirement and disability benefits.

"Why are these guys taking aim at Social Security now?" the former president asked. "They're following that old line from tech startups - the quote is 'move fast, break things.' They're shooting first and aiming later."

"My friend Gov. O'Malley knows what they're really up to, he says, and I love this quote - they want to wreck it so they can rob it," Biden went on. "Why do they want to rob it? To deliver huge tax cuts to billionaires and big corporations and keep it going."

Wearing a blue suit and tie, and standing in front of American flags, the 82-year-old Democrat spoke for around a half-hour.

Biden's choice of topic, Social Security, aimed to ramp up pressure on Trump over his rampaging government overhaul efforts.

He highlighted staff reductions at the agency that Trump and his billionaire aide Elon Musk have pushed as part of their "Department of Government Efficiency," saying the Social Security "website is crashing" and hindering retirees from getting their benefits.

Many Americans "literally count on social security to buy food, just to get by," Biden said, and "many of these beneficiaries, it's their only income. If it were cut or taken away, it would be devastating, devastating for millions of people."

Agencies