Should Kerry apologize?

So the RNC is demanding Kerry apologize for being caught on mike saying the Repubs are corrupt and a bunch of liars.

Of course Kerry can't just do as they say since it will look bad for him to acquiesce too much.  I would love for him to say "Allow me to explain" and catalogue all the asshole things the GOP has been up to going back to SC in 2000 or beyond into the Clinton years.

But how would that really play politcally?  Maybe then the GOP could score points saying he's the one being so divisive and polarizing, not our huggable GWB.  My gut says Kerry should go for the jugular.  But how far is too far in this year's climate?