“Research shows that a vice-presidential candidate determines very few people’s votes,” says Paul Light, an expert”‰on the vice-presidency at New York University. “But it is one of the first big tests of a nominee’s decision-making and helps set the tone for the campaign.”
Economic expertise is likely to be another requirement given Mr McCain’s self-declared weakness on the issue. Executive experience, preferably outside Washington, would be another advantage to balance Mr McCain’s decades of legislative service on Capitol Hill.
Mr McCain’s main strategic decision will be the ideological identity of his running mate. As a Republican moderate, he is under pressure from conservatives to pick someone from the right of the party, such as Rick Perry, the governor of Texas, or Sam Brownback, senator for Kansas.
Many experts believe Mr McCain needs a conservative running mate, preferably from the south, to unify the fractured Republican base. But others argue he has most to gain from picking a fellow moderate, such as Chuck Hagel, senator for Nebraska, or Joseph Lieberman, the independent senator for Connecticut, who would reinforce his appeal among swing-voters. Another option might be Michael Bloomberg, the independent New York mayor and billionaire media tycoon, who recently ended speculation that he might make his own third-party run for president.