[Julian E. Zelizer is a professor of history and public affairs at Princeton University. He is the author of "Jimmy Carter" published by Times Books and editor of a book assessing former President George W. Bush's administration published by Princeton University Press.]

...During its first week, "Sarah Palin's Alaska" attracted almost five million viewers, the best that a premiere has done on the TLC network....

The launch of the show has felt very much like the start of a presidential campaign.

If this turns out to be true, Palin's reality show could be a harbinger of campaigns to come. We might be witnessing the start of a new era in presidential campaigning, where candidates take their message directly to the voters while avoiding almost any filters in the process.

For much of the 20th century, party bosses played the central role in the nomination process. In the famous world of "smoke-filled rooms," party leaders determined which candidate would be best. They evaluated a number of factors, ranging from party loyalty to regional appeal before deciding on the ticket. Primaries had existed for much of the 20th century, but they were not central....