Romney is not as weak as you think.  You are correct that he is the default candidate.  He has a partnership with all the major right-wing media folk--they all endorse him form Coulter, to Drudge, to Michael Medved, etc.  In fact, McCain's "Bomb, Bomb, Iran" clip was apparently leaked to Drudge by Romney's campaign.  The right wing media are all on board with him.  He's the money candidate.  I'm sure that financial "compensation", either direct or indirect, has helped cement his status with the republican elite.

He's also not as weak of a candidate as you think.  He is a very slick and smooth salesman.  He exudes  a "soothing" aura of masculinity, confidence, and competence.    He also has the money and the backing of corporate America.  He can afford a strong campaign infrastructure, has the media on his side, and doesn't make big mistakes.

Be careful who you wish for!

Thanks,

Mike