"Good Morning America" promoted Lara Spencer to co-host and then BURIED the announcement -- presumably to keep some pretty fragile GMA egos in check.
ABC honchos sent an internal memo around to the staff bragging about how GMA has kicked the "Today" show's ass for 2 straight years. The memo -- which was obtained by Page Six -- starts out by calling Robin Roberts "the captain of our team"
In PARAGRAPH 6 the memo essentially says, "Oh, by the way, Lara's a co-anchor now."
And get this ... to make sure the announcement got buried, it was sent to the staff on Good Friday.
Now for some translation ... Lara made lots of demands when her contract was renegotiated recently ... she thinks of herself as Robin's fill-in. She also can't stand Amy Robach -- even though they told TMZ they love each other -- and when Amy got promoted to news anchor apparently GMA felt it needed to up Lara's title to keep her happy.
As for why the announcement was made on Good Friday, well ... people on the staff say Robin can be quite a diva, and GMA didn't want to ruffle her feathers.