So far Mitt Romney has succeeded in keeping his vice presidential deliberations a secret.  At times, it has appeared Romney’s search committee consisted of just three people: Romney himself, wife Ann, and top aide Beth Myers.  At some point — it’s not clear whether it has happened yet — Romney will have to extend the circle, at least a little, to run his thoughts past trusted aides and confidants who can offer extra perspective.  That’s when there’s a heightened danger of the news leaking; for that reason, Romney will likely do that late in the process.

But that doesn’t mean outsiders know nothing about what is going on.  That’s because there are people who know Mitt Romney, who know how he works, and who have been a part of decisions he has made in the past.  And their impressions of Romney offer insights into Romney’s secret deliberations now.  Some of those insights:

1. Romney is innately cautious. Consider the most outside-the-box, game-changing choices Romney might make — and throw them out.  Romney will most likely follow his instinct and go right down the middle with the safest, most do-no-harm pick.

2. Romney is instinctively unflashy. To use a reference to the last Republican nominee, Romney is not a man who would fly his plane under the bridge. He wouldn’t go for the thrill — but he wouldn’t lose the plane, either.

3. Romney believes the boss is the boss. The vice presidential candidate is not the leader of the ticket, and he doesn’t decide the direction of the campaign. Romney is in charge and won’t change his direction to accommodate a running mate.

4. Romney believes his current course is working. He sees staying nearly even with a wealthy incumbent, and keeping that incumbent under 50 percent, is the right foundation for ultimate victory in November. He doesn’t need a big, showy, and possibly risky vice presidential choice to get there.

5. Romney chooses experience. When Romney considers a vice president and is given a choice between a talented newcomer and an equally talented but more experienced veteran, his instincts will tell him to go with experience.

What does that mean for Romney’s current deliberations?  It means he will most likely pick Ohio Sen. Rob Portman, but might go with former Minnesota Gov. Tim Pawlenty.  Portman has experience as a representative, a senator, and a top official in the executive branch; he is an entirely plausible president should something happen to a President Romney.  In addition, unlike Pawlenty, Portman might help Romney win Ohio, and if Romney does not win Ohio, he will not win the presidency.

Of course, the same is true of Florida — if Romney doesn’t win there, he won’t become president.  It’s possible Sen. Marco Rubio would help Romney win Florida , but Rubio doesn’t have Portman’s experience, is still a somewhat unknown quantity, and would also possibly overshadow Romney on the campaign trail — a situation Romney has no interest in creating.

Finally, there is Wisconsin Rep. Paul Ryan.  Ryan is the only one of the four finalists who, if chosen, would fundamentally alter the course of the Romney campaign.  Choosing Ryan would instantly elevate the Ryan budget plan to the top of the Romney agenda.  Some Republicans want to see that, but that is not how Romney has run his campaign so far.  Although he has mostly endorsed the Ryan plan, Romney has from the very start stressed job creation far more than entitlement reform or any other issue.  Romney has thought very carefully for a long time about this campaign; it is highly unlikely that he is planning to change his direction now.

So Romney will very likely go with the least risky choice — Portman — or possibly Pawlenty.  Romney did not get where he is by throwing the dice, and he’s not going to start now.