Mr. Wasserman predicted a significant number of freshmen GOP lawmakers this November would be political newcomers. Many are running on a platform of fiscal rectitude, a nod to how the economy and role of government are dominating public debate. "We really are at a defining moment," Mr. Rigell said in an interview, during which he echoed a theme of economic uncertainty voiced by other candidates. "I look at the fiscal side of this country and I am alarmed and deeply troubled."