Robert Christian points out that one clue to the GOP's failure in the New York special election can be found in the Pew political typology. The key group Corwin lost ground with seems to corresponds to what Pew calls "Disaffecteds." Who are "Disaffecteds"? Pew explains:

The most financially stressed of the eight typology groups, Disaffecteds are very critical of both business and government. They are sympathetic to the poor and supportive of social welfare programs. Most are skeptical about immigrants and doubtful that the U.S. can solve its current problems. They are pessimistic about their own financial future. ...
Defining values: A majority believe that the government is wasteful and inefficient and that regulation does more harm than good. But nearly all say too much power is concentrated in a few companies. Religious and socially conservative.
Who they are: About three-quarters (77%) are non-Hispanic white and two-thirds (66%) have only a high school education or less. Compared with the national average, more are parents (44%). Fully 71% have experienced unemployment in their household in the past 12 months. About half (48%) describe their household as “struggling.”

Disaffecteds tend to lean pretty heavily toward the Republican Party:

Paradoxically, though, they're more resistant to cutting Medicare and Social Security than any other group, including any of the groups that make up the Democratic base:

If you can't read that, only 15% of Disaffecteds favor cuts to Medicare or Social Security to reduce the deficit. Even 26% of "Solid Liberals" favor this.

So here you have a key part of the Republican base, whose swing toward the GOP in 2010 was a crucial factor in the party's success. And this group opposes cutting Medicare more staunchly than any other group. The Ryan plan seems almost designed to blow up the Republican coalition.