With the Supreme Court having already decided on President Obama’s health care law and the news cycle relatively sparse, we’re starting to reach the stage of the campaign when there will be rampant speculation as to who Mitt Romney will pick as his vice presidential running mate. But as you listen to all the talk, it’s worth keeping in mind that in recent history, presumptive nominees haven’t announced their running mates until right before the party convention.

As you can see from the table I created above, in nearly every instance since 1980, vice presidential picks were announced either during the convention or within a week of the start of the convention. The one exception was when John Kerry picked John Edwards on July 6, 2004 — 20 days before the start of that year’s Democratic convention. This year’s Republican National Convention will start in Tampa on August 27,  exactly 7 weeks, or 49 days, from now. So it would break with tradition for Romney to announce his pick any time soon, and it probably wouldn’t make much sense. What if, for instance, between now and the convention there’s some major international crisis that makes national security a more important issue. Romney may be more inclined to consider somebody with foreign policy experience under such circumstances. The bottom line is that Romney would be better off waiting as long as possible to make his choice so he has the most information he can when making his final decision.