There is no question but that the GOP is not fully united as the convention approaches.The primary campaign was brutal and during the time when the candidates were active Mitt Romney struggled to get above 40% in many states.
There are obviously a considerable number of supporters of Ron Paul, of the Tea Party, and Sarah Palin. There are those who are suspicious of Romney's commitment to conservative principles and of course there is the establishment faction.
To have any chance of winning in November, and the electoral college barrier is formidable, the GOP must be totally united and all factions must vote for the nominated candidate for president. It seems to many observers that at present the party is not united and the choice of a vice-presidential running mate is not necessarily the unifier that will ensure a massive turnout of committed rank and file Republicans.
No matter who Romney chooses it will not satisfy all factions. Pawlenty, Christie, Rice, Rubio and others who have been mentioned all have their detractors from left to right and if chosen by the Romney team will clearly be seen as being imposed from above.
If however the decision is given to the convention then the chosen person will have the blessing of the entire party in a show of unity, most probably in a motion to make the decision unanimous after the winning candidate has reached a majority of delegates votes on the day. With the ticket being composed of the winner of the primary battles and the unanimous choice of the convention for the second spot after a due nomination and ballot process the GOP could leave Tampa united and ready to take on the Obama administration without any internal distractions.
Such a process has been an historic reality for nominating conventions and there is absolutely no reason why it could not be put not effect this year. Stevenson did it in 1956 and Roosevelt did it in 1944. Harding's choice for his running mate was rejected by the convention which chose Coolidge instead which united the party
Further it has the added benefit of showcasing up and coming talent for future years. John F. Kennedy was introduced to the wider public at the 1956 Democratic convention when Adlai Stevenson, after he received the presidential nomination, asked the convention to choose his running mate. Kennedy and Estes Kefauver, the eventual winner, battled it out and the ticket was unified whilst Kennedy received the publicity which helped his later career.
With the party not united if Romney not only invited Sarah Palin to the convention but decided to let the delegates choose his running mate I believe it would show Romney had leadership. He would show the capacity for compromise, It would make him a unifier, and would strengthen the party by the Reaganite process of inclusion.