Senate Republicans are preparing to implement a sophisticated, multipronged plan to confirm President Bush’s expected nomination to replace ailing Supreme Court Chief Justice William Rehnquist. Well-funded liberal groups are also ramping up their efforts to block any conservative nominee. Activists working with White House and Senate staffers say the 80-year old Rehnquist’s battle with thyroid cancer has sharply focused attention. The controversy over comments that Sen. Arlen Specter (R-Pa.), incoming Judiciary Committee chairman, made downplaying the chances of anti-abortion-rights nominees being confirmed also accelerated planning. “The groups on the center-right are prepared to mobilize at a moment’s notice,” said Jay...