Alarmed at the chance that the Republican party might pick Rudolph Giuliani as its presidential nominee despite his support for abortion rights, a coalition of influential Christian conservatives is threatening to back a third-party candidate in an attempt to stop him. The group making the threat, which came together Saturday in Salt Lake City during a break-away gathering during a meeting of the secretive Council for National Policy, includes Dr. James Dobson of Focus on the Family, who is perhaps the most influential of the group, as well as Tony Perkins of the Family Research Council, the direct mail pioneer...