Romney is, of course, exiting his job as Governor after an unimpressive one term (and is likely expected to move back to Utah). He has been utterly unable, despite modest attempts, to rebuild the destroyed Massachusetts State Republican Party, which was eviscerated, after a modest comeback at the end of the Dukakis era, by the horrid Weld-Cellucci-Swift regimes. The governorship is expected to effortlessly return to the Democrats.
Although it must be noted that Romney was utterly hamstrung on the job, solely because the Governorship (as long as any Republican occupies it) has been largely stripped of any authority (he is, for example, unable even to appoint a temporary successor to the U.S. Senate if Kerry or Kennedy resign or die). Romney can't really point to any credible accomplishments as a result, and really cannot make any argument that he has the "experience" required to serve as President.
There are better other people in the running.
Okay, Romney couldn't walk on water in MA. I'll agree. And the republican party is eviscerated. What the heck's wrong with us? (No guts, no glory.)