This innocent-looking thing does a good job hiding its defects.
Readability can be much improved by merely moving the subgroup labels ("All", "Democrats", etc.) to the left border of the chart.
The proportion of respondents who are Democrats, Independents and Republicans, if printed on the chart, will help us understand how the bottom three bars relate to the top one. As it is, we can reason that there were roughly equal proportions of Democrats and Republicans (the Independents are somewhat like the overall average, and the overall average is roughly at the midpoint between the Republican and the Democrat numbers).
And the colors!! Where to begin?
It used to be that color was banished from "good" graphics because it was considered unnecessary, and more trouble than its worth. We now embrace color with moderate enthusiasm. This chart shows why colors should be used judiciously.
If asked to provide a color key to this chart, one may come up with the following:
It appears that 8% of Democrats have been banned from wearing party colors because of their white flag on health care; ditto the 42% of Republicans who wanted health care reform.
The colors should be coordinated with the structure of the data. Here, the data has three dimensions: the answer to the question, the party affiliation, and party v. overall average. For this graph, I reckon the answer to the question is the most important dimension.
Finally, I think by highlighting the 88% of Democrats and 55% of Republicans, the chart actually missed the information in the data: that 42% of Republicans actually supported health care reform -- my impression is that the 55/42 split among Republicans makes this a much more bipartisan issue than most other issues in U.S. politics. In other words, the fact that most Democrats support the liberal position and most Republicans support the conservative position is just not news.
Reference: "Poll: bipartisanship popular, compromise tricky", Washington Post, Feb 9, 2010.