It's a shift in whom you get to pick up, to identify and vote for you, and to feel trust in your ideas and the general outlook of your party. Obama didn't get the majority of the white (non-hispanic, non-mixed) vote, but he got a larger part of it than any Democrat has got since the 1960s, since the Civil Rights era, and that's a real shift in voter sympathies (Lyndon Johnson foresaw that many southern whites would give up on the Democrats after the Civil Rights Act).

And the "pure white" vote is shrinking as a part of the American people, so it becomes less and less viable to run the Reagan/Rove strategy where you base yourself on Conservatives and right-wing christians and then try to catch the middle field by sizing up the Dems as a haughty snob elite and launching personal attacks. The Hispanics largely feel the Democrats are their party, so do most Afro-Americans and many people who have good earnings and academic careers also dropped the GOP in the Bush years; the beginning financial and industrial crisis is likely to keep up that tendency cause many people seem to feel it's been brought on by the thinking and the policies of the Bush years (imo you can't separate the astronomical costs of the Iraq war effort from the pressure on the dollar, the deficit and the impact that it's had on wages and purchase power, which in turn has made many people take loans for consumption or just to pay off earlier loans).

So if one sticks to candidates like Romney, Giuliani or Palin (they all might run in '12) it will attract those "smalltown Americans" but it'll have a hard time catching a majority, either in the popular vote or in key states like Ohio, Nevada, Minnesota, N/S Carolina or Pennsylvania. The time for that kind of nominee is running out.