WASHINGTON — On Wednesday morning Donald Trump and Melania Trump will depart the White House as president and first lady, but they will not invite their incoming counterparts, Joe and Jill Biden, inside before they do.

The dissolving of one of America's most enduring transfer-of-power rituals — the outgoing president welcoming the incoming president on the steps of the North Portico, and then riding with them to the United States Capitol — is just one of the snubs from the Trumps as they leave Washington.

Instead of a president and a first lady, the Bidens will be greeted by White House chief usher Timothy Harleth, according to a source familiar with the day's events and planning. Harleth, a 2017 Trump hire from the Trump International Hotel in Washington, will likely not stay on in the Biden administration, the source said, noting the role of chief usher in all probability will be filled by someone more familiar with the incoming president and first lady.

Trump, according to several sources, is even mulling whether to write a letter to Biden to leave for him in the Oval Office, a standard-bearing tradition.

Melania Trump has reportedly not reached out to Jill Biden, dashing expectations she would continue the tradition of hospitality to her successor, hosting her for a tour.

Melania Trump did post a "farewell message" on Twitter on Monday:

The afternoon of Inauguration Day, then-President Biden will participate in a ceremonial wreath-laying at Arlington National Cemetery, joined by former Presidents Bill Clinton, George W. Bush and Barack Obama. It is during these hours the bulk of the Bidens' personal effects will be moved into the White House and unpacked, according to another source with knowledge of executive residence practices.

By that time, all Trump paraphernalia will be gone, and a thorough top-to-bottom cleaning of the entire White House campus will have been completed. Deeper cleaning protocols were arranged via the White House with outside contractors, on top of regular cleaning done by staff, including specialized attention to rugs, carpets, curtains and surfaces, to tackle any possibility of lingering germs, of the COVID-19 sort or otherwise.

A particular focus of this move will be paid to the bedrooms in the residence, where new mattresses and box springs for the incoming first family are standard operating procedure, according to the source. Yet one part of the bedroom set-up will be markedly different with the Bidens than it was for the Trumps: The Bidens will be sharing a bedroom. Melania Trump spent the majority of her time in the White House in the large bedroom suite typically reserved for presidents and their spouse, adjacent to the West Sitting Hall, according to a source with knowledge of the arrangement.

"Donald Trump slept in his own bedroom, which was previously a study or den during other administrations," the source said of the arrangement.

On Monday, moving trucks were spotted in the driveways of Mar-a-Lago in Palm Beach, Fla., with movers loading dollies of boxes and items and rolling them into the private club, which will serve as the Trumps' post-White House home, which is the plan for now, said another source with knowledge of the planned living arrangements and security arrangements set in place.

The Inauguration Day snub of the Bidens comes on the heels of a series of broken norms from the president, who for months refused to concede the election to Biden.

But even after contentious election cycles in the past, first ladies and presidents have set aside hard feelings and ego, no matter how bruised — until now.

Small measures of decorum during the transition are being practiced, however. CNN has learned of at least three Trump administration officials who used private communication channels to reach out to their Biden administration counterparts in the last month.

Over the weekend, Trump's official White House photographer Shealah Craighead was spotted by CNN giving a tour of the White House photo office to Adam Schultz and Chandler West, Biden's incoming official photographer and photo editor, respectively. While photographers mark one end of the spectrum, Vice President Mike Pence would signal the other.

On Thursday, Pence spoke with Vice President-elect Kamala Harris for the first time, the highest-level contact to date between the outgoing and incoming administrations. Their conversation was described as cordial, with Pence offering his congratulations and assistance, according to a person familiar with the matter.

On Sunday, the Pences were still doing official duties, visiting troops at Fort Drum in New York. Karen Pence was emotional referring to her last official trip during her remarks.

"Here I go," she said, pausing between sentences at a podium inside the hangar, trying to catch herself before more tears rolled down her face. "It is such an honor to be here with you."

Photos: Inauguration preparations underway

See the scene in Washington, D.C., as Inauguration Day nears.