The prolonged collapse of the marriage of Prince Charles and Lady Diana has brought the British monarchy embarrassment and ridicule at home and abroad. Critics say the sordid details behind the failed marriage have destroyed the royal family's image as an exemplar of stability and propriety. They also contend that the monarchy undermines governmental accountability and democratic processes. But supporters say the monarchy promotes national unity, preserves historic traditions and acts as a check against political abuse. Critics want a national referendum on abolishing the monarchy and establishing a republic after Queen Elizabeth's death. But no major politician has taken up the issue. And polls indicate that most Britons favor keeping the monarchy - even though they also doubt its long-term survival.