WASHINGTON — President Trump arrives in the Oval Office these days as late as noon, when he is usually in a sour mood after his morning marathon of television.

He has been up in the White House master bedroom as early as 5 a.m. watching Fox News, then CNN, with a dollop of MSNBC thrown in for rage viewing. He makes calls with the TV on in the background, his routine since he first arrived at the White House.

But now there are differences.

The president sees few allies no matter which channel he clicks. He is angry even with Fox, an old security blanket, for not portraying him as he would like to be seen. And he makes time to watch Gov. Andrew M. Cuomo’s briefings from New York, closely monitoring for a sporadic compliment or snipe.

Confined to the White House, the president is isolated from the supporters, visitors, travel and golf that once entertained him, according to more than a dozen administration officials and close advisers who spoke about Mr. Trump’s strange new life. He is tested weekly, as is Vice President Mike Pence, for Covid-19, the disease caused by the coronavirus.