Jay Bookman nails it:
In his tweets urging Romney to “draw clear line: offer specific path,” [Rupert] Murdoch hits on one probable cause for the GOP nominee’s aversion to specifics: “Stop fearing far right which has nowhere else to go.”
Romney understands that the policy specifics that would be acceptable to his party’s base would be unacceptable to the general-election voter, and vice versa. So he grimly refuses to go there, judging that the cost of silence will be lower than the cost of clarity. His entire presidential campaign has been built around the goal of establishing himself as “severely conservative,” to use his own description, and he has internalized that goal to such a degree that he simply doesn’t dare to put that reputation at risk.
The problem is, there’s no reason to believe that he would show any more independence while governing than he has in campaigning. As Grover Norquist said back in February, “We are not auditioning for fearless leader. We don’t need a president to tell us in what direction to go. We know what direction to go … We just need a president to sign this stuff. We don’t need someone to think it up or design it.”
That’s the job description that Romney is attempting to fill.