It shouldn't surprise anyone that Jeb Bush, in an interview with the AP, is pushing Marco Rubio for VEEP. Jeb thinks Rubio is ready and was pushing him in a recent meeting with Romney.
Of course Jeb's pushing of Rubio is also self serving. Both Jeb and Rubio have their eye on the White House in 2016, and getting him out of the way now, would clear a path for Jeb in 2016 and prevent the two from fighting over FL voters.
If Rubio were to accept the VEEP and lose, he could get a black eye from the fight and be tarred with the stink of a loser.
And despite media attention, Rubio is widely seen as a flawed national candidate because of his financially plagued past.
If Rubio wins, being VEEP could end his presidential ambitions. Despite popular belief, only one VEEP in the last 100 years has been elected POTUS from the Vice President's residence (GHW Bush).
And finally, all of this is probably just academic. ABC News is insisting Rubio isn't even being vetted (even as Romney says he is). Rubio himself is insisting he will not take the job if offered and seems to really mean it -- He's running for President.
It won't be Rubio. Romney's VEEP will be Rob Portman running on the whitest ticket since Ford / Rockefeller.