A report from MSNBC on Monday suggests that Joe Biden is within 48 hours of announcing his decision on whether to run for president. Forty-eight hours! That's the briefest window yet.

But don't be surprised if we miss it.

Since the beginning of the year, there has been a wide array of reported and speculated rumors about when a Biden announcement would be coming. In February, Biden said "end of summer," which of course has come and gone. Since then, the window has narrowed and moved and expanded repeatedly — not always thanks to direct comments from Biden or his aides, but in the reporting of the media.

Notice that the timeline eventually began to converge onto late October. We can put this into mathematical terms. As the date (x) has approached Oct.  31, the decision has approached 1.

It might  come as early as Tuesday, when Biden is expected to give a speech called "The Mondale Vice Presidency and Its Legacy."

Historians will remind you that, when he ran for president in 1984, Walter Mondale received the least electoral votes of any candidate since 1936.