Meanwhile, both the Democratic Congressional Campaign Committee and National Republican Congressional Committee are engaged in the race, which has quickly vaulted to national attention. 

The NRCC released a new TV spot Monday hitting Hochul as a puppet of House Democratic leader Nancy Pelosi (D-Calif.). The NRCC ad buy is close to $411,000, airing on broadcast and cable in Rochester and Buffalo's media markets, according to a GOP operative.

The Tea Party group FreedomWorks announced an effort to mobilize its grassroots forces against Davis in the district last week, denouncing Davis as "a fraud."

The group said it was coordinating with local Tea Party activists in the district to organize door-to-door canvassing efforts and ask its members across the country to participate in phone banking efforts targeting Davis.  

Sean J. Miller contributed to this report.