In principle, if you got everyone to agree to it (and this would be a big if), this would probably be an interesting enough ticket that it might just win. Maybe.
In practice, Romney is 77 years old and is ready to retire - and think how often age has come up as a factor in the presidential race recently. Romney isn't running for reelection, but if he had wanted his senate seat for another 6 years, I am quite certain it would have been his. So ultimately, I don't think Romney would go for it, simply because he wants to spend more time with his (large) family.
In practice, Romney is 77 years old and is ready to retire - and think how often age has come up as a factor in the presidential race recently. Romney isn't running for reelection, but if he had wanted his senate seat for another 6 years, I am quite certain it would have been his. So ultimately, I don't think Romney would go for it, simply because he wants to spend more time with his (large) family.