Obama has won the white vote in the following primaries and caucuses - Iowa, Alaska, Colorado, Idaho, Illinois, Kansas, Minnesota, New Mexico, North Dakota, Utah, Nebraska, Washington, Maine, Virginia, Hawaii, and Wisconsin.
Of this group, my personal view is that the significant results were in Iowa, Colorado, Minnesota, New Mexico, Nebraska, Washington, Virginia and Wisconsin. In those states I believe you can reasonably argue that Barack Obama is more electable than Hillary Clinton and that it matters (for example it does not matter that Obama is more electable in Illinois nor does it matter that Hillary Clinton is more electable in New York. It does not matter that Barack Obama is more electable in Utah and it does not matter that Hillary Clinton is more electable in Oklahoma. These states are NOT in play.)
What state did Barack Obama's inability to garner more women, seniors, Latinos and white working class voters hurt him and his electability? You know the roster, Ohio, Pennsylvania, Texas, Florida (with the asterisk if you like). Michigan we do not know.
It is as simple as this - if Obama can not do better with these groups, then the traditional Democratic electoral map for winning in November is at more risk with Obama than with Clinton. Of course, Obama is also an electoral map expander - see Colorado, Iowa, Nevada, Virginia, etc.
The choice is the same as it always was - the higher risk, higher potential benefit of Obama versus the more secure path with less potential benefit of Hillary Clinton.
Indiana is a favorable ground for Obama to assuage the fear of the risks. It is next to Illinois. Northern Indiana is a Chicago suburb. It is an Open Primary. He has all the money in the world. He has nothing to fear in North Carolina (a narrow or wide victory does not matter). He can go all out in Indiana to finish Hillary Clinton off in this race. By beating her in Indiana.
To do that he must do better with white working class voters and white women. It is that simple. Indiana is a fair test. Not because Indiana will be in play in November (it won't.) But because the demographics give Obama the test he must pass to resolve the electability doubts.