This was just posted at Ace's.
Mitt Romney to endorse Marco Rubio.
No other details yet.
UPDATED: More info here on the courageous Mitt and how he took the leadership reigns into his capable hands. Curious that Romney managed to tip his hand so soon after the Crist campaign started to circle the drain. Almost as if he wet his finger and tested the winds.
How it does help is that many retires from New York and Massachusetts will feel more at ease voting for a conservatives when such noted moderates have endorsed Rubio.