I see your point, but have a strong suspicion that the election would just be fought out on TV to an even greater extent, with more mudslinging and rumor-mongering. Traditional city/country campaign rallies would become a fixture, but mainly as audience competitions. But the internet and broadcast media would become more critical than ever, and accuracy or integrity haven't exactly been at a premium in large-scale election campaigns.
Things like subsidies to special interest groups would become even more common since the payoff in terms of votes would be higher. Increase the corn subsidy and you don't just buy Iowa but corn farmers everywhere.
That would be around 1 million potential voters out of 235 million total. My suspicion is that attention would shift towards numerically larger special interest groups.
