Late last month, House Republican leaders gathered in Newt Gingrich's office to hear some sobering news from the man who tracks the party's chances in November's election. John Linder's message, contained in a confidential memo in advance of the April 23 meeting, was simple: the G.O.P. could lose its narrow 11-seat majority in the House if it didn't find a way to galvanize its grass-roots activists, many of whom are Christian conservatives.
Linder's audience knew to take the message seriously, because for months they had been hearing the same thing, and worse, from an even more indisputable source: James Dobson, the...