By Eric Bradner

CNN

WASHINGTON (CNN) -- Donald Trump has arrived in Washington -- and he's going to be here for at least four years.

The reality of the moment, that the real estate mogul and reality show star will recite the oath of office Friday, is finally taking hold.

Republicans and Trump's still-growing staff are set for a celebration. Trump and Vice-President elect Mike Trump go through the ceremony at the Capitol at noon, followed by a parade up Pennsylvania Avenue -- and past Trump's new hotel -- to be followed by a weekend of balls and an anticipated flurry of new executive actions Monday.

The transition of power -- from a Democratic president to a Republican one -- has shut down much of Washington and left its thousands of political staffers in quiet anticipation.

At the same time, President Barack Obama's last boxes are being packed and his few remaining aides are preparing to move out as they enter their last moments hours of Obama's eight years in the White House.

Obama is spending the last full day of his presidency in the White House on Thursday, where staffers are saying their wistful goodbyes.

"After six years here, walking through these doors for the final time," White House deputy press secretary Eric Schultz tweeted.

Outgoing White House Press Secretary Josh Earnest tweeted his thanks to the press corps. "It's been an honor to serve. And to all those fighting for a better future, I'll see you on the other side. Thanks," he wrote.

All around them, Washington is hustling to prepare for Trump's swearing-in on the steps of the Capitol.

Barricades are up all around the Capitol building and traffic has ground to a halt through downtown Washington, as the Secret Service restricts access to an event where the President-elect, outgoing President, much of Congress and the Supreme Court will be on-hand.

DC workers are also navigating around the closures of five Metro stops -- Mount Vernon Square, Archives, Federal Triangle, Smithsonian and the Pentagon.

Out-of-towners are streaming into Washington hotels, and small protests are popping up day and night around the Capitol complex.

One unexpected bit of inauguration-week drama: Questions over whether the National Park Service would set aside its ban on umbrellas, with rain forecast for Friday's inauguration.

The decision: Long umbrellas still won't be allowed. But attendees can bring small, collapsible umbrellas.

On Capitol Hill, members of the Senate are gearing up for an immediate battle over confirming Trump's Cabinet picks.

About seven nominees may receive confirmation votes Friday afternoon, after Trump's inauguration, while Democrats are already looking to draw out the process with some of the picks, like secretary of state nominee Rex Tillerson and HHS nominee Tom Price.

Obama held his final news conference Wednesday -- and his final interview was with a podcast run by a group of former aides, Tommy Vietor, Jon Favreau, Jon Lovett and Dan Pfeiffer.

In his final news conference, Obama offered an optimistic message as his party prepares to watch Republicans reverse many of its accomplishments from his tenure in office.

"It is true that behind closed doors, I curse more than I do publicly, and sometimes I get mad and frustrated like everybody else does," Obama said. "But at my core, I think we're going to be OK. We just have to fight for it, we have to work for it and not take it for granted."

After Trump's inauguration, Obama and his family will depart on one last presidential plane ride -- to a vacation in Palm Springs, California. They'll travel back on their own.