It's national players like the Club for the Growth that are trying to defeat Scozzafava.

Scozzafava was selected as the candidate by her local Republican Party committee. Presumably, they would like to win the election. Presumably, they would like to keep this seat Republican. Presumably, they remember the special election held in upstate New York earlier this year, where an unknown Democrat beat a well-known Republican even though the district had a majority of registered Republicans. Presumably, they picked someone moderate in order to better satisfy their local electorate.

The viability of moderate Republican candidates is being destroyed by so-called conservative Republicans.

Scozzafava's defeat would mean the end of moderate Republicans as viable candidates even in liberal states like New York.

Go tea party!