Both Chris Cillizza and James Pethokoukis, in their case for a Romney/McCain ticket, cite the former Mass. governor's economic bona fides as giving him top billing in the selection process.

Cillizza, however, notes another benefit:

But picking a candidate who can appeal to a broad group of influential voters across several states will never go out of style. (Joe Lieberman's appeal to Jewish voters in 2000; Lyndon Johnson's ability to deliver the South for John F. Kennedy in 1960 etc.)

Romney fits squarely into the latter category in two swing states -- Nevada and Colorado. The former Massachusetts governor's Mormonism makes him an extremely appealing vice presidential candidate and could well tip a narrow race in McCain's favor.

This is particularly true in Nevada where it is is estimated that nearly eight percent of the state's population is Mormon and where, according to one Romney backer, Romney is a "rock star."

Aside from Romney's appeal among Mormons, he also can help win two more states: New Hampshire and Michigan.

Although Romney lost the New Hampshire primary to McCain, his status as the ex-governor of a neighboring state makes him a known commodity there. Republicans already feel good about their chances of winning this state, which Kerry won in 2004.

Romney's Michigan roots -- he was born there and his father served as the state's governor -- played a major role in his Wolverine State primary win. The Romney brand is perhaps at its strongest in Michigan and, when coupled with his business background and familiarity with the struggles of the automobile industry, a strong case can be made that putting Romney on the ticket makes McCain a slight favorite over Obama in the state.

Based on these back-of-the-envelope calculations, Romney improves the chances of victory for the Republican ticket in at least four states. What other vice presidential hopeful can say the same?

Romney won Nevada in the primaries, both mostly because he was the only one to really compete there. Still, Cillizza's contention that Romney could play well out West is one to consider.

If McCain did choose Romney critics would quickly jump on the "Two Old White Guys" theme. Which might or might not affect voters. If it does, it will affect voters on the fence and perhaps women, who would be looking for either ticket to have a woman . So the question is whether Romney's appeal and economic credentials outweigh the need to have a diversified ticket.