I have my doubts that the primary voters in the democratic party would ever nominate someone from, or who had been part of, the military leadership establishment. Too many democratic rank and file voters are highly suspicious of the military brass in this country, and would be likely to think that anybody who has spent that many years in the Pentagon couldn't be that progressive, nor could they possibly be as open to cutting military or defense spending in favor of social spending. Clark seems progressive, it may be who is, but he can't change what he is, and that is military.

Also I see it as very difficult for someone in Clark's position to win because unless you are billionaire and can buy support, you really need an electoral base. You've got to have supporters, base from which to start. Clark skipped Iowa four years ago I think in part because he had no base nor political history, and thus no network of elected officials and democratic party reps there to make winning caucuses feasible. He can't run in Iowa this time for the same reasons, and also because the voters there don't forget and won't forgive him for skipping out four years ago. If he can't compete in Iowa, he'll never win New Hampshire because voters there expect candidates to be paying their dues in both big early states. Without Iowa or New Hampshire, where does he start from, where does he get his momentum thus enabling him to raise money?

So I think you're right, he might be running to set himself up for a shot to be Hillary's (or Obama's) vice president. He petitioned Kerry four years ago for the job, he wants it. But what I've heard indicates he may not get it, as Mark Warner has skipped the race himself and turned down other offers to be available to be Hillary's #2 and Virginia is a more crucial state in the general election than Arkansas so it probably makes more sense.