There has been no video of the president making an announcement, and the White House is apparently planning no press conference or official act of any kind. Biden has not been seen by anyone except his inner circle in days. (We can contrast this situation with Lyndon Johnson's televised address announcing his withdrawal from the 1968 presidential campaign.) 

This is, in the words of Glenn Greenwald, "strange." Moreover, Biden's silence is inexplicable if Biden actually made the decision to withdraw from the race. After all, Greenwald, notes, if Biden is "well enough to decide, then he's well enough to speak." Yet, following one of the most important announcements of his political career, Biden has disappeared, and few things could better illustrate how irrelevant Biden now is to the matter of who is actually running the executive branch of the United States government. (We do have some audio of him speaking on a Monday phone call.) 

A chain of events like this is characteristic of a palace coup—something along the lines of the 1991 August Coup in the Soviet Union, had it succeeded. In such cases, the chief executive is marginalized and replaced at the discretion of high-ranking bureaucrats and elites from within the ruling government itself. 

It's too early to get many facts about the details of what threats may have been used against Biden to get him to effectively step aside in favor of Kamala Harris.  What we do know, however, is that the president is essentially absent and it is Harris who is conducting public events at the White House. 

So, who is running the executive branch and the White House?

The fact that Biden himself is clearly not equipped for such a task has been undeniable since his performance at the presidential debate with Donald Trump last month. Since then, the official gaslighting propaganda about how Biden is "sharp as a tack" has been exposed as an obvious lie.