A Political Irony

In the heat of this political year I've noticed something of a political irony that has been around for a long time.  Some candidates are quick and loud to proclaim they are conservatives.  I see political signs and literature that say the candidate is a conservative and believes in conservative principles.  Yet, I see no political signs where candidates proclaim to be a liberal.  What is it about being a liberal they don't want people to know?  Are they ashamed to be a liberal?  Are they hiding something?  Do they know that if they proclaim to be a liberal they will never win an election?  But, once elected they govern as liberals.  How ironic!