There’s a school of thought in the extended Romney camp that the identity of the pick will dictate the timing of the announcement. A choice that is more exciting to the Republican base, and to the GOP convention delegates, can be announced late, even at the convention itself, because it will instantly excite Republican loyalists. No need for an extended sales campaign. But a pick that is less exciting to the base might be announced earlier, to give Romney time to build support for his choice.

“If he picks Rubio, he could do that the day before the convention, and it would electrify the convention and be exciting,” says one source who is familiar with the campaign but not part of the vice presidential process. “[The delegates] want Rubio, or maybe Christie, or perhaps Paul Ryan. But if he chooses Portman or Pawlenty, he should do it enough in advance so that he doesn’t immediately go in and disappoint the convention. It gives him time to sell his choice.”