Michael Barone‘s latest column probes presumptive Republican presidential nominee Mitt Romney’s options for a running mate. Rather than pursue a ticket-balancing approach, Barone suggests Romney might go for the “double vanilla” option, a second white male.

Four possibilities come to mind. One is Paul Ryan, the House Budget Committee chairman who endorsed Romney and campaigned with him all over Wisconsin. Romney has praised Ryan’s budget proposals and has endorsed the fundamentals of Ryan’s Medicare plan.

Ryan’s in-depth knowledge of budget numbers surely appeals to Romney. The strongest argument against a Ryan nomination is that a President Romney would need him championing his budget and entitlement plans in the House.

Another possible choice is Senator Rob Portman, who campaigned all over Ohio with Romney. Like Romney, Portman comes from a family with Midwestern manufacturing-management experience.

But he’s also served in the House and as special trade representative and budget director. And he’s had experience in presidential campaigns: He played Democratic nominees in debate prep for Dick Cheney in 2000 and 2004 and John McCain in 2008.

Two governors should make any short list, Mitch Daniels of Indiana and Bob McDonnell of Virginia. Daniels also served as budget director for Bush and is a crusader for entitlement reform. McDonnell has ties to the military as a longtime reservist and as the father of a daughter who served in Iraq.

All four of these potential vanilla running mates take conservative stands on cultural issues but are careful to show respect for those who differ. All have emphasized economics in their campaigns and have run especially well in affluent suburbs, as Romney has in Republican primaries.