WASHINGTON >> President-elect Donald Trump used a raucous rally Sunday on the eve of his inauguration to promise swift Day 1 action remaking the federal government, shifting federal priorities at breakneck speed and ensuring that “the curtain closes on four long years of American decline.”

Supporters filled nearly all of the 20,000-plus-seat Capital One Arena in downtown Washington for a “Make America Great” victory celebration, and cheered as Trump said he’d take quick action on everything from cracking down on the U.S.-Mexico border to promoting oil drilling, reining in the federal workforce and eradicating diversity programs.

“We’re going to give them the best first day, the biggest first week and the most extraordinary first 100 days of any presidency in American history,” said Trump, who also promised to roll back executive actions by his predecessor, outgoing President Joe Biden, “within hours.”

In an unusual move, Trump entered at the arena’s concourse level and deliberately made his way down the stairs before his speech, stopping frequently to pump his fist and pose for pictures with rallygoers.

Trump said he’d jump start his agenda with a series of unilateral actions from the White House, telling the crowd, “You’re going to see executive orders that are going to make you extremely happy. Lots of them.”

“Tomorrow we will not waste a single moment,” he vowed later to attendees at a dinner reception.

Sunday was Trump’s first full day back in Washington since his Election Day victory and gave him a chance to energize core supporters before the official pomp of Inauguration Day. Unlike when Trump helped spark a mob of his supporters to attack the Capitol and tried to retain power in 2021 after his loss to Biden, officials did not expect massive protests, unrest or violence.

Instead, jubilant crowds reveled in Trump’s second term and MAGA’s total control of the Republican Party.

Trump has insisted that unity will be a theme of his inauguration speech Monday, along with strength and fairness — despite spending months as a candidate saying that if elected he would seek retribution against political enemies.

That was the theme of much of his rally speech Sunday, when Trump returned to the greatest hits of his campaign — as if the race against Vice President Kamala Harris weren’t already long decided. Trump denounced “migrant crime” by evoking one of his favorite fictional characters, Hannibal Lecter, and promised to stamp out “woke” policies and oppose transgender rights.

“Tomorrow, at noon, the curtain closes on four long years of American decline, and we begin a brand new day of American strength and prosperity, dignity and pride,” Trump said, adding, “Once and for all, we’re going to end the reign of a failed and corrupt political establishment in Washington.”

Billionaire Tesla owner Elon Musk — who Trump has tasked with helping run a special commission to make the federal government more efficient — took the stage and said “we’re looking forward to making a lot of changes.”

With frigid temperatures expected Monday, Trump directed most of Monday’s outdoor events to be moved indoors, and officials held a rehearsal Sunday for his swearing-in in the U.S. Capitol’s Rotunda, which holds only 600 people compared to the 250,000-plus guests who had tickets to view the inauguration from around the Capitol grounds.