I really hope that John McCain does not pick Mitt Romney as his VP. I have to qualify this statement by saying that I think Romney was by far the best candidate for president - I'd love to see him as president or as vice president but I hope he is not McCain's choice. Let me explain.
Mitt Romney is a good person. He is a member of The Church of Jesus Christ of Latter-day Saints (Mormons) and lives his religion. He has a great family, so I hear, and has done great things for many people and businesses. He's been hugely successful in the business world and even managed to get elected as a Republican governor in Massachusetts, not an easy task. During campaigning many people accused him of being a "flip-flopper" on issues. Yes, he changed position on some issues but he wasn't a "flip-flopper". This undeserved stigma will be hard to lose. It would be hard for me to watch the media crucify Romney because he would not deserve it. Of course he has his faults but they are not generally what the media says are his faults.
As a Mormon, there is a significant portion of the Republican (and Democratic) Party that will not vote for him. For them, having a Mormon in the White House is like being condemned to Hell for eternity. I wish I was joking. While this bigotry hopefully decreases over time, it's still a significant factor. This anti-Mormon portion of the Republican Party is large enough that they could seriously impact McCain's chance for election should McCain choose Romney as his VP. They already are not very trustful of McCain as it is.
I also would like Romney to run for president in 2012 and/or 2016. If he was McCain's VP and McCain was elected, that would mean that we would have had 12 to 16 years of Republican presidents (and by the time Romney's term(s) was over it would have been 16 to 20 years), which might be more than the country would think it could handle. We usually like to alternate between Republican and Democratic presidents with some frequency. This is actually also one reason why I think it might be good for Obama to win. Maybe after 4-8 years of his presidency our country would be ready for another Republican (or an Independent).
Of course, it is possible that as VP, Romney's chances for the presidency would increase because people would see that Mormons are fairly normal and get more used to the idea of a Mormon in the White House. While I'd love it if Romney was picked the VP, I'm not sure if it would be the best thing for Romney's chances for the Presidency in the future.
In a move that shows both political awareness and good character, Mitt Romney will endorse John McCain for president. Many might question his motives - is he seeking for nomination as a running mate? Maybe. Is he trying to consolidate the Republicans in order to muster the strength to beat the Democrats? Yes. Is he reaching out to McCain to build bridges that were torched during a sometimes acerbic campaign? Yes. Again, Romney is showing that he can put the interests of the country and party ahead of his own ambitions. Some may argue that putting a "liberal" like John McCain in office is not helping the country. However, Romney realizes that "liberal" McCain is more than a stone throw conservative than either Democratic candidate.
I am always amazed at how good Mitt Romney is (good as in a honest person with good character and values). I shouldn't be amazed but in the context of general American politics, it's easy to become jaded about politicians. Romney isn't a politician though. He was a governor and tried to get into politics in the 1990s but he's a businessman, a family man, and a conservative who happens to have held political office. Romney's endorsement will seal the nomination for McCain (even though McCain will still be a few delegates shy of the total needed, assuming all of Romney's delegates decide to support McCain).