Question re: Political Thinking

Since November we've been hearing on a fairly regular basis how the 2012 campaign has begun, how the potential contenders on one side are jockeying for position and now we're hearing that the current President's administration is focusing on re-election.  The thought is that by diverting a portion of his attention to the campaign now, the President can still, with diminishing attention to the needs of the country and the world, continue to lead throughout the term.  My question is this:  Should a person elected to office spend any of their time while in office campaigning for re-election?  Asked in another way, why can't the fruits of your labor be your best advertisement? 

It reminds me of a story I heard of a man being told that he hadn't gotten the promotion he'd worked so hard to win.  He had wined the right people, dined the right people, played golf with the right people.  All the while, the person who got the promotion was the one who went about his job with dilligence. 

Can our political system work that way?  I fear that it cannot.  Why do politicians campaign so often, pander to special interests and cozy up to lobbyists?  Money.  Money to pay for 30 second sound bites.  Why the 30 second sound bites?  Why not the strength of your accomplishments?  The 30 second sound bite works better.  The general public spends so little time studying political races that name recognition alone can generate a win on election day.  In some locations it's the little letter next to the name that signifies the win.  In others, it's simply the spelling of your last name. So, if we're not going to judge our politicians on the strength of their accomplishments, then we certainly can't expect them to try so hard for them, can we?