US President Donald Trump said on Saturday that “nobody's ever seen anything" like his administration's sweeping effort to fire thousands of federal employees and shrink the size of government, congratulating himself for “dominating” Washington and sending bureaucrats “packing.”

Addressing an adoring crowd at the Conservative Political Action Conference just outside Washington, Trump promised, “We’re going to forge a new and lasting political majority that will drive American politics for generations to come.”

The president argues that voters gave him a mandate to overhaul government while cracking down on the US-Mexico border and extending tax cuts that were the signature policy of his first administration.

Trump clicked easily back into campaign mode during his hour-plus speech, predicting that the GOP will continue to win and defy history.

Trump has empowered Elon Musk to help carry out the firings, and the billionaire suggested Saturday that more might be coming.

“Consistent with President @realDonaldTrump’s instructions, all federal employees will shortly receive an email requesting to understand what they got done last week,” Musk posted on X, which he owns. “Failure to respond will be taken as a resignation.”

A short time later, an “HR” email was sent to federal workers across numerous agencies titled “What did you do last week” and asking that recipients “reply with approx. 5 bullets of what you accomplished last week and cc your manager.” It cautioned against sending classified information, and gave a deadline of just before midnight on Monday.

Trump also said during the speech that he'd carry out harsher immigration policies. But those efforts have so far largely been overshadowed by his administration's mass federal firings.

Trump also devoted large chunks of his address reliving last year's presidential race, jeering at former President Biden and mispronouncing the first name of former Vice President Kamala Harris - his Election Day opponent - gleefully proclaiming, “I haven’t said that name in a while.”

Trump had kinder words for President Xi Jinping , saying “I happen to like” him. (AP)