Obama is like the Tide Laundry Detergent of this Democratic nominating cycle: He's a proven winner, someone people believe in strongly and are willing to forego a little more coin (ex. the gas tax) for.

George McGovern went so far as to switch sides after initially saying it was time for 'ladies first' and backed Clinton. People choose the candidate or 'brand' they feel is more successful, a subconscious choice if the candidate has the power and money to advertise to them like Obama does.

Read more about the power of the political brand here, happy to answer questions and receive comments:

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