Many people think that a presidential candidate must choose a running mate who provides the ticket with geographic, demographic, or ideological “balance.” During the past academic year, my student Jake Petzold wrote a terrific senior thesis debunking this notion. Since the days of FDR, he explained, the only time that balance played a decisive role was 1960, when Lyndon Johnson helped John Kennedy carry Texas and some other Southern states. More often, ticket-balancing has created problems. On paper, conservative Midwestern Baby Boomer Dan Quayle was a great match for moderate Texas/New England World War II veteran George H.W. Bush. In the real world of the 1988 race, Quayle’s stumbling performance proved to be a major distraction.

Mitt Romney knows this history. Accordingly his vice presidential selection process is reportedly stressing the potential candidates’ qualification for high office, with balance as a secondary consideration. In this light, it is easy to see why Senator Marco Rubio (R-Florida) may be in eclipse. At first glance, a young conservative Hispanic from a big swing state might seem a good complement to Romney. If he were the vice presidential nominee, however, Democrats would attack his scanty national credentials (less than two years in the Senate).   Moreover, his demographic appeal might be weaker than his admirers hope. In describing their identity, a recent poll shows, most Hispanic Americans prefer their family’s country of origin over pan-ethnic terms. People with roots in Mexico, Puerto Rico, and South America might not identify with a Cuban American.  And while Romney wants the election to be about the economy, putting Rubio on the ticket would mean endless questions about immigration.

Senator Rob Portman (R-Ohio) would add neither ethnic appeal (Swiss-Americans are a rather small bloc) nor glamour (no relation to Natalie Portman).  But he has a strong background:  in addition to serving in the House and Senate, he has been director of the Office of Management and Budget and the U.S. Trade Representative.  He also has been around presidential campaigns, prepping GOP candidates by portraying various Democrats in mock debates. And though vice presidential candidates usually add only a couple of points to the ticket in their home states, that small increment could tip closely-contested Ohio, which in turn could tip a tight battle in the electoral college.

Nevertheless, Portman has a big problem named Bush.  The attack ad writes itself:  “As George Bush’s budget director, Rob Portman delivered deficits.  As George Bush’s trade representative, Rob Portman shipped jobs overseas. As Mitt Romney’s vice president, he’d do both.”  Yes, such attacks would be wildly inaccurate, but they’d draw some blood.  As JFK said, life is unfair.

There is also talk of former Minnesota governor Tim Pawlenty. He appeals to social conservatives yet also won statewide races in a state known for electing liberals.  He has solid executive experience, but since he’s never been a member of Congress, he doesn’t have a list of roll call votes to explain. Still, there is reason to wonder whether he would be a strong national candidate.  His brief bid for the GOP presidential nomination collapsed before the primaries got under way.

Of course, Romney might stun the political community with a running mate that nobody’s talking about right now – the political equivalent of a Hail Mary pass.  That’s probably not a good idea.  As Sister Anna Gregory taught me many years ago, Hail Marys are no substitute for correct choices.