If Marco Rubio of Florida were the Republican presidential nominee, could he pick Jeb Bush of Florida as his running mate?
Absolutely, yes, no doubt about it.
There is regularly confusion over this. Major newspapers have reported falsely that the Constitution prohibits a one-state ticket, or that the candidates on such a ticket would forfeit their right to their home state's Electoral College votes. These things are false. There are surely political reasons to not have a single-state ticket, or to not pick Jeb Bush as your running mate, but the Constitutional issue is much smaller than many people think, and in the hypothetical case of a 2016 Rubio-Bush ticket, it's basically a non-issue.
For 2016 the slight difficulty boils down to this: If the GOP nominated a Rubio-Bush ticket, and they won in a close election, it might be left to the Republican-controlled Congress--rather than the Electoral College--to actually elect either Rubio or Bush.Read more on WashingtonExaminer.com