Personally, I don't think she could just because most moderates I have spoken with would not vote for her over Obama. If she can't win the moderate vote or the liberal vote, that leaves her only staunch conservatives.
“Never give in. Never give in. Never, never, never, never, in nothing great or small, large or petty, never give in except to convictions of honor and good sense. Never yield to force. Never yield to the apparently overwhelming might of the enemy.” - Winston Churchill