I don't think so. They'll remember how many Republicans treated the first African-American President, the dog whistles, the birthers, etc. Plus, Obama will probably be campaigning for whoever the Democratic nominee will be. And once you vote in 2 elections, chances are that you'll keep voting for the rest of your life.
Ahh I disagree. Look at the Saxby Chambliss 2008 race. It's a three point race with the Democrat close behind on the day Obama is on the ballot. One month later, Obama is off the ballot, and the Democrat falls 14% behind. Not a coincidence.