Republican or Democrat? Switching parties after election is false advertising!

I have been thinking a lot about effects and consequences when an elected official switches parties...certainly brought to light after the Arlen Specter event recently. I believe that many people vote for candidates based on their party affiliation, and if a candidate switches parties after being elected, couldn't that be construed as a betrayal to the voters? Or false advertising?

It seems like the voters should at least have an opportunity to elect someone else, or confirm that person again after switching. I don't think it is fair, or representative of the voters' wishes if someone changes parties after being elected without the voters having some validation.

What do you think?