Obama asking for Republican Votes

GIven the complaints about Rush Limbaugh suggesting that Republicans in Texas, I thought that this story was interesting:

The [Obama] campaign is running radio ads in Pittsburgh and Philadelphia to urge students, independents and Republicans -- three key voting blocks -- to register as Democrats before the March 24 deadline. . . .

I lost the link to this quote, but I believe that it was from the Tribune-Review in Pittsburgh.