From http://news.yahoo.com/president-obama-suggests-romney-shoveling-load-know-171643214–abc-news.html :

The visit was an “official” presidential event, not campaign-related, but the odd dynamic when the president took the stage to chants of “Four More Years!” after which a labor official told the crowd, “This is not a political event.”
That seemed a questionable assertion, given how the president continually referenced Romney, defending how his moves to save GM and Chrysler demanded change and accountability.

Why the façade? I understand that the President has the bully pulpit. Fine. So, why call it an “official visit” when you are visiting a state on the day that it votes and blast your opponent? You are in campaign mode, I get it. So why not just call it what it is.

Candor is an important part of my campaign, and my outlook on life. If I try to describe my behavior in nonsensical or defensive ways please call me out on it. When elected I will, of course, spend some of my time as your congressman campaigning. It’s one of the core activities on the job – explaining what I’ve done, what I’m doing, what I want to do, and drawing distinctions with my opponents who want to do something else. I won’t call it “official business” I’ll call it “campaigning” and then people won’t accuse me of obfuscation.