There is good reason for Mitt Romney to wait until close to the convention to pick his running mate, and not simply to keep the TV ratings from plummeting. Campaigns take on a life of their own, exposing weaknesses and creating opportunities. What Romney might have looked for in a VP earlier in the race (e.g. reassurance for the base) doesn’t look so important now. Other considerations have moved up (e.g., a worldwide economic slowdown).

There are a couple of months to go, but here are eight considerations for Romney in making his VP pick:

1. Can articulate a free-market message. Romney is making a convincing case that the president is in over his head, at a loss to understand what ails the economy and how to fix it. The more help Romney can get in this department and the more vigorously a VP can spell out the flaws in the Obama economic policy, the better.

2. A calm and reassuring demeanor. Romney is being painted as a wide-eyed extremist bent on gutting government. The former Massachusetts governor with a center-right record doesn’t fit that bill (to the dismay of President Obama’s spinners), and he should select someone who is likewise an improbable “radical.” While the VP must often play the role of attack dog, it will pay off to choose someone who can do it with a smile and good cheer.

3. Solid in the Midwest. At this point Romney could very well break through in blue states such as Iowa, Michigan and Wisconsin. He’ll also need to keep Ohio in his column. It’s not been fashionable in recent election cycles to choose a VP to nail down a home state, but in this case finding a running mate who is effective and well known in a crucial part of the country is a plus.

4. Boring is fine. Much has been made of Ohio Sen. Rob Portman’s lack of pizzazz. But that seems like a trivial concern right now. In a campaign in which the presidential nominee is selling himself as mature and experienced and Obama is turning out to be the bore, charisma should be relatively irrelevant in Romney’s VP selection concerns.

5. A reformer. Romney is not running as the candidate of “no,” but as the candidate who can use common-sense conservative principles to solve our problems. Someone with a reputation for innovation or for deal-making, rather than an intransigent partisan, would reinforce this message.

6. National security experience is a plus. Romney could well encounter some foreign policy crises during the campaign, and, if elected, would certainly see his share of national security challenges. It pays to have someone on the ticket with national security know-how (gained either in Congress or in the military).

7. Find someone with whom Romney gets along. Campaign staffers and pundits have noted that when Ann Romney is present at campaign events with her husband he is more relaxed and more effective as a speaker. Although a VP won’t be with Romney all the time, there will be many side-by-side events and likely a few interviews with the two of them. It’s beneficial if the VP and Romney have, for lack of a better description, some chemistry and Romney can be looser and more at ease in his or her presence.

8. Diversity shouldn’t be the controlling factor. The surest way to botch a VP rollout is to have the running mate remind voters of Sen. John McCain’s lightly vetted VP. The voters and press will smell a “token” a mile away, and Romney will blow his reputation as a seasoned executive if he picks an obscure or relatively inexperienced running mate.