Romney offers as much or more than they do, particularly with his experience in business at this point in time. He believes he’s the best person for the job, as do they. Furthermore, they have plenty more time. Why should Romney step down and get out of the way?
Because he's a liberal, and he knows he is, anyone with half a brain KNOWS he is.
Supported directly Planned Parenthood with funds AND appeared at functions.
Instituted socialized medicine in his state while he was Governor.
Supported gun-grabbing and basic trampling of 2A rights as Governor.
But now he's changed?
HELLO!!!
He's done it in the PRIMARIES!
Who knows (other than the Living Prophet® of the LDS Organization) whether McCain would have had a TERMINAL episode and left the field ripe for picking?