Introduction

Richard Drew/Associated Press

Under pressure from his fellow Democrats, Representative Anthony Weiner resigned on Thursday.

He had sent sexually explicit photos and messages to several women, and had initially denied doing so. While there is no evidence (thus far) that he broke the law or committed adultery, the scandal was hurting his party's efforts to keep public attention on Medicare and other issues.

Will his quick resignation make such distractions more common, as political operatives from both parties scrutinize their rivals' lives for embarrassing revelations? Democrats and some Republicans are asking: What about Senator David Vitter of Louisiana, a family-values Republican, who hired prostitutes and, in at least one instance, tried to book one while he was on the House floor. He had brushed aside reports that he had consorted with hookers until his name appeared in the records of a Washington prostitution ring. But Mr. Vitter weathered the storm, and was re-elected. What determines which politicians can stay and who will be forced to go?